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  <DIV align="center" style="font-size: 10pt; margin-top: 18pt">As filed with the U.S. Securities and Exchange Commission on May 15, 2006
  </DIV>
  
  
  <DIV align="right" style="font-size: 10pt; margin-top: 12pt">Registration
  No.&nbsp;333- _________<BR><BR>
  </DIV>
  
  
  <DIV style="width: 100%; border-bottom: 2pt solid black; font-size: 1pt">&nbsp;</DIV>
  <DIV style="width: 100%; border-bottom: 1pt solid black; font-size: 1pt">&nbsp;</DIV>
  
  
  
  
  <DIV align="center" style="font-size: 14pt; margin-top: 12pt"><B>UNITED STATES SECURITIES AND EXCHANGE COMMISSION</B>
  </DIV>
  
  <DIV align="center" style="font-size: 12pt"><B>Washington, D.C. 20549</B>
  </DIV>
  
  
  <DIV align="center">
  <DIV style="font-size: 3pt; margin-top: 16pt; width: 26%; border-top: 1px solid #000000">&nbsp;</DIV>
  </DIV>
  
  
  
  <DIV align="center" style="font-size: 18pt; margin-top: 12pt"><B>FORM S-8</B>
  </DIV>
  
  
  <DIV align="center" style="font-size: 12pt; margin-top: 12pt"><B>REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933</B>
  </DIV>
  
  <DIV align="center" style="font-size: 24pt; margin-top: 12pt"><B>CABOT CORPORATION</B>
  </DIV>
  
  <DIV align="center"><DIV style="font-size: 3pt; margin-top: 1pt; width: 50%; border-top: 1px solid #000000">&nbsp;</DIV></DIV>
  
  <DIV align="center" style="font-size: 10pt">(Exact name of registrant as specified in its charter)</DIV>
  
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
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      <TD width="47%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="47%">&nbsp;</TD>
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  <TR valign="bottom">
      <TD align="center" valign="top"><B>Delaware</B><BR>
  (State or other jurisdiction<BR>
  of incorporation or organization)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top"><B>04-2271897</B><BR>
  (I.R.S. Employer<BR>
  Identification No.)</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <DIV align="center">
  <DIV style="font-size: 3pt; margin-top: 16pt; width: 26%; border-top: 1px solid #000000">&nbsp;</DIV>
  </DIV>
  
  
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="47%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="47%">&nbsp;</TD>
  </TR>
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  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD align="center" valign="top"><B>Two Seaport Lane<BR>
  Suite&nbsp;1300<BR>
  Boston, MA</B><BR>
  (Address of principal executive offices)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top"><B>02210</B><BR>
  (Zip Code)</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>Cabot Corporation 2006 Long-Term Incentive Plan<BR>
  Cabot Corporation Non-Employee Directors&#146; Stock Compensation Plan</B><BR>
  (Full title of the plan)
  </DIV>
  
  
  <DIV align="center">
  <DIV style="font-size: 3pt; margin-top: 16pt; width: 26%; border-top: 1px solid #000000">&nbsp;</DIV>
  </DIV>
  
  
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 12pt">Brian A. Berube, Esq.<BR>
  Vice President and General Counsel<BR>
  Two Seaport Lane<BR>
  Suite&nbsp;1300<BR>
  Boston, MA 02210<BR>
  <U>(Name and address of agent for service)</U>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt">617-345-0100<BR>
  <U>(Telephone number, including area code, of agent for service)</U>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt">CALCULATION OF REGISTRATION FEE
  </DIV>
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="1%">&nbsp;</TD>
      <TD width="41%">&nbsp;</TD>
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      <TD width="2%">&nbsp;</TD>
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      <TD width="1%">&nbsp;</TD>
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      <TD width="2%">&nbsp;</TD>
      <TD width="9%">&nbsp;</TD>
  
      <TD width="1%">&nbsp;</TD>
  </TR><TR style="font-size: 1px" valign="bottom">
      <TD nowrap align="left" colspan="19" style="border-bottom: 3px double #000000">&nbsp;</TD>
  </TR>
  <TR style="font-size: 8pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
  
      <TD>&nbsp;</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Proposed Maximum</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Proposed Maximum</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 8pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
  
      <TD nowrap align="left">Title Of Securities</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center">Amount To Be</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Offering Price Per</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Aggregate Offering</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center">Amount Of</TD>
      <TD width="1%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 8pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
  
      <TD nowrap align="left">To Be Registered</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center">Registered (1)</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Share</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">Price</TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center">Registration Fee</TD>
      <TD width="1%">&nbsp;</TD>
  </TR>
  
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      <TD width="1%" style="border-top: 1px solid #000000">&nbsp;</TD>
                      <TD valign="top" style="border-top: 1px solid #000000"><DIV style="margin-left:0px; text-indent:-0px">Common Stock,
  Par Value $1.00 per
  share
  </DIV></TD>
      <TD style="border-right: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
      <TD style="border-top: 1px solid #000000">&nbsp;</TD>
      <TD align="center" nowrap valign="top" style="border-top: 1px solid #000000">4,850,000 shares (2)
  </TD>
      <TD style="border-right: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
      <TD style="border-top: 1px solid #000000">&nbsp;</TD>
      <TD nowrap align="right" valign="top" style="border-top: 1px solid #000000">$</TD>
      <TD align="right" valign="top" style="border-top: 1px solid #000000">35.235</TD>
      <TD nowrap valign="top" style="border-top: 1px solid #000000">(3)</TD>
      <TD style="border-right: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
      <TD style="border-top: 1px solid #000000">&nbsp;</TD>
      <TD nowrap align="right" valign="top" style="border-top: 1px solid #000000">$</TD>
      <TD align="right" valign="top" style="border-top: 1px solid #000000">170,889,750</TD>
      <TD nowrap valign="top" style="border-top: 1px solid #000000">(3)</TD>
      <TD style="border-right: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
      <TD style="border-top: 1px solid #000000">&nbsp;</TD>
      <TD align="left" valign="top" style="border-top: 1px solid #000000">$18,285.21 (3)</TD>
      <TD width="1%" style="border-top: 1px solid #000000">&nbsp;</TD>
  </TR>
  <TR style="font-size: 1px" valign="bottom">
      <TD nowrap align="left" colspan="19" style="border-top: 3px double #000000">&nbsp;</TD>
  </TR>
  
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="1%" nowrap align="left">(1)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Pursuant to Rule 416(a) under the Securities Act of 1933, this registration statement also
  covers such additional shares of Common Stock as may become issuable under the plans to
  prevent dilution from stock splits, stock dividends and similar transactions.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="1%" nowrap align="left">(2)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>The shares of Cabot Corporation common stock being registered hereby include (a)&nbsp;4,500,000
  shares to be offered under the 2006 Long-Term Incentive Plan; and (b)&nbsp;350,000 shares to be
  offered under the Non-Employee Directors&#146; Stock Compensation Plan.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="1%" nowrap align="left">(3)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Estimated solely for the purpose of calculating the registration fee pursuant to Rules 457(c)
  and 457(h) of the Securities Act of 1933, as amended, and based upon the average of the high
  and low prices of the Common Stock as reported on the New York Stock Exchange Composite Tape
  on May&nbsp;10, 2006.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="width: 100%; border-bottom: 1pt solid black; margin-top: 10pt; font-size: 1pt">&nbsp;</DIV>
  <DIV style="width: 100%; border-bottom: 2pt solid black; font-size: 1pt">&nbsp;</DIV>
  
  
  
  
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
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  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  
  
  
  
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>PART 1<BR>
  INFORMATION REQUIRED IN THE SECTION 10(A) PROSPECTUS</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;1. Plan Information.</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The information required by Item&nbsp;1 will be included in documents sent or given to participants
  in the plan covered by this registration statement pursuant to Rule&nbsp;428(b)(1) of the Securities Act
  of 1933, as amended (the &#147;Securities Act&#148;).
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;2. Registrant Information and Employee Plan Annual Information.</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The written statement required by Item&nbsp;2 will be included in documents sent or given to
  participants in the plan covered by this registration statement pursuant to Rule&nbsp;428 (b)(1).
  </DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>PART II<BR>
  INFORMATION REQUIRED IN THE REGISTRATION STATEMENT</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;3. Incorporation of Documents by Reference.</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The following documents filed with the Securities and Exchange Commission (the &#147;Commission&#148;)
  pursuant to the Securities Exchange Act of 1934, as amended (the &#147;Exchange Act&#148;) by Cabot
  Corporation (the &#147;Registrant&#148;) (Commission File No.&nbsp;1-5667) are incorporated in this Registration
  Statement by reference and shall be deemed to be a part hereof:
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(a)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>The Registrant&#146;s Annual Report on Form 10-K for the fiscal year ended September
  30, 2005, as filed with the Commission on December&nbsp;14, 2005;</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(b)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>The Registrant&#146;s Quarterly Report on Form 10-Q for the quarterly period ended
  December&nbsp;31, 2005, as filed with the Commission on February&nbsp;9, 2006;</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(c)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>The Registrant&#146;s Quarterly Report on Form 10-Q for the quarterly period ended
  March&nbsp;31, 2006, as filed with the Commission on May&nbsp;10, 2006;</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(d)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>The Registrant&#146;s Current Reports on Form 8-K as filed with the Commission on
  May&nbsp;4, 2006, February&nbsp;9, 2006, February&nbsp;2, 2006, January&nbsp;19, 2006, January&nbsp;10, 2006,
  December&nbsp;27, 2005, December&nbsp;13, 2005, November&nbsp;23, 2005, November&nbsp;3, 2005, and October
  17, 2005;</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(e)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>The description of the Registrant&#146;s Common Stock, $1.00 par value per share,
  contained in the Registrant&#146;s Registration Statement on Form&nbsp;10, filed with the
  Commission pursuant to Section&nbsp;12 of the Exchange Act.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;All documents subsequently filed by the Registrant pursuant to Sections&nbsp;13(a), 13(c), 14 and
  15(d) of the Exchange Act, prior to the filing of a post-effective amendment to this Registration
  Statement that indicates that all securities offered have been sold or which deregisters all
  securities then remaining unsold, shall be deemed to be incorporated herein by reference from the
  date of filing of such documents. Any statement contained in this Registration Statement, in an
  amendment hereto or in a document incorporated or deemed to be incorporated by reference herein
  shall be deemed to be modified or superseded for the purposes of this Registration Statement to the
  </DIV>
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
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  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">extent that a statement contained herein or in any other subsequently filed document that also is
  or is deemed to be
  incorporated by reference herein modifies or supersedes such statement. Any statement so
  modified or superseded shall not be deemed, except as so modified or superseded, to constitute a
  part of this Registration Statement.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;4. Description of Securities.</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Not applicable.
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;5. Interests of Named Experts and Counsel.</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Brian A. Berube, the Registrant&#146;s Vice President and General Counsel, has opined as to the
  legality of the issuance of the Common Stock being registered under this Registration Statement.
  At the time of rendering his opinion, Mr.&nbsp;Berube had a substantial interest in the Registrant, as
  defined by the rules of the Commission, in that the fair market value of the approximately 54,000
  shares of Common Stock owned by him exceeds $50,000. It is anticipated that additional shares will
  be issued to Mr.&nbsp;Berube pursuant to the 2006 Long-Term Incentive Plan and under other employee
  benefit plans of the Registrant.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;6. Indemnification of Directors and Officers.</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Section&nbsp;145 of the Delaware General Corporation Law, as amended, provides that a corporation
  may
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;indemnify any person who was or is a party or is threatened to be made a party to any threatened,
  pending or completed action, suit or proceeding, whether civil, criminal or investigative (other
  than an action by or in the right of the corporation) by reason of the fact that such person is or
  was a director, officer, employee or agent of the corporation, or is or was serving at the request
  of the corporation as director, officer, employee or agent of another corporation, partnership,
  joint venture, trust or other enterprise, against expenses (including attorneys&#146; fees), judgments,
  fines and amounts paid in settlement actually and reasonably incurred by such person in connection
  with such action, suit or proceeding if such person acted in good faith and in a manner such person
  reasonably believed to be in or not opposed to the best interests of the corporation, and, with
  respect to any criminal action or proceeding, had no reasonable cause to believe such person&#146;s
  conduct was unlawful. Section&nbsp;145 further provides that a corporation similarly may indemnify any
  such person serving in any such capacity who was or is a party or is threatened to be made a party
  to any threatened, pending or completed action or suit by or in the right of the corporation to
  procure a judgment in its favor, against expenses actually and reasonably incurred in connection
  with the defense or settlement of such action or suit if such person acted in good faith and in a
  manner such person reasonably believed to be in or not opposed to the best interest of the
  corporation and except that no indemnification shall be made in respect of any claim, issue or
  matter as to which such person shall have been adjudged to be liable to the corporation unless and
  only to the extent that the Delaware Court of Chancery or such other court in which such action or
  suit was brought shall determine upon application that, despite the adjudication of liability but
  in view of all the circumstances of the case, such person is fairly and reasonably entitled to
  indemnity for such expenses which the Court of Chancery or such other court shall deem proper.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Section&nbsp;102(b)(7) of the Delaware General Corporation Law, as amended, permits a corporation
  to include in its certificate of incorporation a provision eliminating or limiting the personal
  liability of a director to the corporation or its stockholders for monetary damages for breach of
  fiduciary duty as a director, provided, however, that such provision shall not eliminate or limit
  the liability of a director (i)&nbsp;for any breach of the director&#146;s duty of
  </DIV>
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
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  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">loyalty to the corporation
  or its stockholders, (ii)&nbsp;for acts or omissions not in good faith or which involve intentional
  misconduct or a knowing violation of law, (iii)&nbsp;under Section&nbsp;174 of the Delaware General
  Corporation Law (relating to unlawful payment of dividends and unlawful stock purchase and
  redemption) or (iv)&nbsp;for any transaction from which the director derived an improper personal
  benefit.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Article&nbsp;Eight (j)&nbsp;of the Registrant&#146;s Certificate of Incorporation and Section&nbsp;14 of the
  Registrant&#146;s by-laws provide that the Registrant shall indemnify any person who was a party, is a
  party or is threatened to be made a party to any threatened, pending or completed action, suit, or
  proceeding by reason of the fact that such person is or was a director, officer, employee or agent
  of the Registrant or is or was serving at the request of the Registrant as a director, officer,
  employee or agent of another company or enterprise, including service as a fiduciary of an employee
  benefit plan, against expenses (including attorneys&#146; fees), judgments, fines, penalties and amounts
  paid in settlement incurred in connection with such action, suit or proceeding to the extent
  permitted from time to time under the Delaware General Corporation Law. Such indemnification shall
  be made as authorized in a specific case upon a determination by the Board of Directors or the
  stockholders of the Registrant. The rights of indemnification are not exclusive of any other rights
  to which those seeking indemnification may be entitled and shall continue as to a person who ceases
  to be a director, officer, employee or agent. In addition, under Article&nbsp;Eight (i)&nbsp;of the
  Registrant&#146;s Certificate of Incorporation no director or officer of the Registrant shall be liable
  to the Registrant or its stockholders for monetary damages for any breach of fiduciary duty, except
  to the extent that Delaware General Corporation Law prohibits the elimination or limitation of
  liability of directors or officers for breach of fiduciary duty.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;All of the Registrant&#146;s directors and officers are covered by insurance policies maintained by
  the Registrant against specified liabilities for actions taken in their capacities as such,
  including liabilities under the Securities Act.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;7. Exemption From Registration Claimed.</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Not applicable.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;8. Exhibits.</B>
  </DIV>
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="90%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="8%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD>
      <TD width="90%">&nbsp;</TD>
  </TR>
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">Exhibit</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="bottom">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px"><u>Number</u>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom"><u>Document Description</u></TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="bottom">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.1
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">Restated Certificate of Incorporation of Cabot Corporation (incorporated by
  reference to Exhibit&nbsp;3.1 to the Quarterly Report on Form&nbsp;10-Q of Cabot Corporation,
  File No.&nbsp;1-5667, filed with the Commission on February&nbsp;9, 2006).</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.2
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">2006 Long-Term Incentive Plan of Cabot Corporation (incorporated by reference
  to Appendix&nbsp;B of Cabot Corporation&#146;s Proxy Statement on Schedule&nbsp;14A relating to the
  2006 Annual Meeting of Shareholders, File No.&nbsp;1-5667, filed with the Commission on
  January&nbsp;30, 2006).</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.3
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">Non-Employee Directors&#146; Stock Compensation Plan of Cabot Corporation
  (incorporated by reference to Appendix&nbsp;C of Cabot Corporation&#146;s Proxy Statement on
  Schedule&nbsp;14A relating to the 2006 Annual Meeting of Shareholders, File No.&nbsp;1-5667,
  filed with the Commission on January&nbsp;30, 2006).</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">5.1*
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">Opinion of Brian A. Berube, Vice President and General Counsel.</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">23.1*
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">Consent of PricewaterhouseCoopers LLP.</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always">&nbsp;</H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="90%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="8%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD>
      <TD width="90%">&nbsp;</TD>
  </TR>
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">23.2*
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">Consent of Brian A. Berube, Vice President and General Counsel (included in Exhibit&nbsp;5.1).</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">24*
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">Power of Attorney (included on the signature page of this registration statement).</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  
  <DIV align="left">
  <DIV style="font-size: 3pt; margin-top: 16pt; width: 18%; border-top: 1px solid #000000">&nbsp;</DIV>
  </DIV>
  
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  <TR>
      <TD width="3%"></TD>
      <TD width="1%"></TD>
      <TD width="96"></TD>
  </TR>
  
  <TR valign="top">
      <TD nowrap align="left">*</TD>
      <TD>&nbsp;</TD>
      <TD>Filed herewith</TD>
  </TR>
  
  </TABLE>
  
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;9. Undertakings.</B>
  </DIV>
  
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(a)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>The undersigned Registrant hereby undertakes:</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="6%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(1)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>To file, during any period in which offers or sales are being
  made, a post-effective amendment to this Registration Statement:</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="10%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(i)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>To include any prospectus required by Section
  10(a)(3) of the Securities Act;</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="10%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(ii)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>To reflect in the prospectus any facts or
  events arising after the effective date of the Registration Statement
  (or the most recent post-effective amendment thereof) which,
  individually or in the aggregate, represent a fundamental change in the
  information set forth in the Registration Statement; and</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="10%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(iii)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>To include any material information with
  respect to the plan of distribution not previously disclosed in the
  Registration Statement or any material change to such information in
  the Registration Statement;</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left"><I>&nbsp;</I></TD>
      <TD width="1%"><I>&nbsp;</I></TD>
      <TD><I>provided, however</I>, that paragraphs (a)(1)(i) and (a)(1)(ii) above shall not apply if
  the information required to be included in a post-effective amendment by those
  paragraphs is contained in periodic reports filed with or furnished to the
  Commission by the Registrant pursuant to Section&nbsp;13 or 15(d) of the Exchange Act
  that are incorporated by reference in the Registration Statement.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="6%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(2)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>That, for the purpose of determining any liability under the
  Securities Act, each such post-effective amendment shall be deemed to be a new
  registration statement relating to the securities offered therein, and the
  offering of such securities at that time shall be deemed to be the initial <I>bona
  fide </I>offering thereof.</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="6%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(3)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>To remove from registration by means of a post-effective
  amendment any of the securities being registered which remain unsold at the
  termination of the offering.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(b)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>The undersigned Registrant hereby undertakes that, for purposes of determining
  any liability under the Securities Act, each filing of the Registrant&#146;s annual report
  pursuant to Section 13(a) or 15(d) of the Exchange Act (and, where applicable, each
  filing of an employee benefit plan&#146;s annual report pursuant to Section 15(d) of the
  Exchange Act) that is incorporated by reference in the Registration Statement shall be
  deemed to be a new Registration Statement relating to the securities offered therein,
  and the offering of such securities at that time shall be deemed to be the initial <I>bona
  fide </I>offering thereof.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always">&nbsp;</H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  <DIV style="margin-top: 6pt"><TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(c)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Insofar as indemnification for liabilities arising under the Securities Act may
  be permitted to directors, officers and controlling persons of the Registrant pursuant
  to the foregoing provisions,
  or otherwise, the Registrant has been advised that in the opinion of the Commission
  such indemnification is against public policy as expressed in the Securities Act and
  is, therefore, unenforceable. In the event that a claim for indemnification against
  such liabilities (other than the payment by the Registrant of expenses incurred or
  paid by a director, officer or controlling person of the Registrant in the
  successful defense of any action, suit or proceeding) is asserted by such director,
  officer or controlling person in connection with the securities being registered,
  the Registrant will, unless in the opinion of its counsel the matter has been
  settled by controlling precedent, submit to a court of appropriate jurisdiction the
  question whether such indemnification by it is against public policy as expressed in
  the Securities Act and will be governed by the final adjudication of such issue.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always">&nbsp;</H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  <DIV style="margin-top: 6pt"><TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  
  
  </TABLE>
  </DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>SIGNATURES</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it
  has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and
  has duly caused this registration statement to be signed on its behalf by the undersigned,
  thereunto duly authorized, in the City of Boston, The Commonwealth of Massachusetts, on this 12th
  day of May, 2006.
  </DIV>
  
  <TABLE width="100%" border="0" cellspacing="0" cellpadding="0" style="font-size: 10pt">
  <TR>
      <TD width="48%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="35%">&nbsp;</TD>
      <TD width="15%">&nbsp;</TD>
  </TR>
  <TR>
      <TD valign="top" align="left">&nbsp;</TD>
      <TD colspan="3" align="left">CABOT CORPORATION<BR>
  &nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR><TR>
      <TD align="left">&nbsp;</TD>
      <TD valign="top">By:&nbsp;&nbsp;</TD>
      <TD colspan="2" style="border-bottom: 1px solid #000000" align="left"><FONT style="font-variant: SMALL-CAPS">/s/ Kennett F. Burnes</FONT>
  &nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR><TR>
      <TD align="left">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD valign="top">Name:&nbsp;&nbsp;</TD>
      <TD align="left">Kennett F. Burnes&nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR><TR>
      <TD align="left">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD valign="top">Title:&nbsp;&nbsp;</TD>
      <TD align="left">President and Chief Executive Officer&nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR>
  <TR>
      <TD colspan="5">&nbsp;</TD>
  </TR>
  </TABLE>
  <!-- link1 "SIGNATURES AND POWER OF ATTORNEY" -->
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>SIGNATURES AND POWER OF ATTORNEY</B>
  </DIV>
  
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Each person whose signature appears below constitutes and appoints Brian A. Berube and Jane A.
  Bell and each of them singly, his or her true and lawful attorney-in-fact and agent with full power
  of substitution and resubstitution, for him or her and in his or her name, place and stead as a
  director or officer or both, as the case may be, of Cabot Corporation, to sign any and all
  amendments (including post-effective amendments) to this Registration Statement on Form S-8 to be
  filed by Cabot Corporation, and all documents or instruments necessary or appropriate to enable
  Cabot Corporation to comply with the Securities Act of 1933, as amended, and to file the same, with
  all exhibits thereto, with the Securities and Exchange Commission, granting unto said
  attorneys-in-fact and agents full power and authority to do and perform each and every act
  whatsoever that is necessary, appropriate or advisable in connection with any or all of the
  above-described matters and to all intents and purposes as he or she might or could do in person,
  hereby ratifying and confirming all that said attorneys-in-fact and agents, or their substitutes,
  may lawfully do or cause to be done by virtue hereof.
  </DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt">* * * *
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Pursuant to the requirements of the Securities Act of 1933, as amended, this registration
  statement has been signed by the following persons in the capacities and on the dates indicated.
  </DIV>
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="40%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="40%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="14%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">
      <TD nowrap align="left"><u>Signature</u></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="left"><u>Title</u></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="left"><u>Date</u></TD>
  </TR>
  
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Kennett F. Burnes
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">Kennett F. Burnes</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director, Chairman of the Board,
  Chief<BR>
  Executive Officer and President<BR>
  (Principal Executive Officer)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May&nbsp;12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Jonathan P. Mason
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">Jonathan P. Mason</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Executive Vice President and Chief
  Financial Officer<BR>
  (Principal Financial Officer)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May&nbsp;12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
  
  <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ James P. Kelly
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">James P. Kelly</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Controller<BR>(Controller/Principal Accounting Officer)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May&nbsp;12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
  
  <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ John S. Clarkeson
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">John S. Clarkeson</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May&nbsp;12, 2006</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always">&nbsp;</H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="40%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="40%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="14%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">
      <TD nowrap align="left"><u>Signature</u></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="left"><u>Title</u></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="left"><u>Date</u></TD>
  </TR>
  
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Juan Enriquez-Cabot
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">Juan Enriquez-Cabot</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May&nbsp;12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Arthur L. Goldstein
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">Arthur L. Goldstein</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May&nbsp;12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Gautam S. Kaji
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">Gautam S. Kaji</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May 12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Roderick C.G. MacLeod
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">Roderick C.G. Macleod</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May&nbsp;12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ John H. McArthur
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">John H. McArthur</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May&nbsp;12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Henry F. McCance
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">Henry </FONT>F. M<FONT style="font-variant: SMALL-CAPS">cCance</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May&nbsp;12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ John F. O&#146;Brien
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">John F. O&#146;Brien</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May 12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Ronaldo H. Schmitz
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">Ronaldo H. Schmitz</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May&nbsp;12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Lydia W. Thomas
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">Lydia W. Thomas</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May 12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Mark S. Wrighton
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">Mark S. Wrighton</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May 12, 2006</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Dirk Blevi
  <DIV style="font-size: 1pt; border-top: 1px solid #000000">&nbsp;</DIV>
  <FONT style="font-variant: SMALL-CAPS">Dirk Blevi</FONT>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">May 12, 2006</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always">&nbsp;</H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>EXHIBIT INDEX</B>
  </DIV>
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="90%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="8%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="87%">&nbsp;</TD>
  </TR>
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">Exhibit</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="bottom">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px"><u>Number</u>
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom"><u>Document Description</u></TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="bottom">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.1
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">Restated Certificate of Incorporation of Cabot Corporation (incorporated by
  reference to Exhibit&nbsp;3.1 to the Quarterly Report on Form&nbsp;10-Q of Cabot Corporation,
  File No.&nbsp;1-5667, filed with the Commission on February&nbsp;9, 2006).</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.2
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">2006 Long-Term Incentive Plan of Cabot Corporation (incorporated by reference
  to Appendix&nbsp;B of Cabot Corporation&#146;s Proxy Statement on Schedule&nbsp;14A relating to the
  2006 Annual Meeting of Shareholders, File No.&nbsp;1-5667, filed with the Commission on
  January&nbsp;30, 2006).</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.3
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">Non-Employee Directors&#146; Stock Compensation Plan of Cabot Corporation
  (incorporated by reference to Appendix&nbsp;C of Cabot Corporation&#146;s Proxy Statement on
  Schedule&nbsp;14A relating to the 2006 Annual Meeting of Shareholders, File No.&nbsp;1-5667,
  filed with the Commission on January&nbsp;30, 2006).</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">5.1*
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">Opinion of Brian A. Berube, Vice President and General Counsel.</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">23.1*
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">Consent of PricewaterhouseCoopers LLP.</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">23.2*
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">Consent of Brian A. Berube, Vice President and General Counsel (included in Exhibit&nbsp;5.1).</TD>
  </TR>
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">24*
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="bottom">Power of Attorney (included on the signature page of this registration statement).</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  
  <DIV align="left">
  <DIV style="font-size: 3pt; margin-top: 16pt; width: 18%; border-top: 1px solid #000000">&nbsp;</DIV>
  </DIV>
  
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  <TR>
      <TD width="3%"></TD>
      <TD width="1%"></TD>
      <TD width="96"></TD>
  </TR>
  
  <TR valign="top">
      <TD nowrap align="left">*</TD>
      <TD>&nbsp;</TD>
      <TD>Filed herewith</TD>
  </TR>
  
  </TABLE>
  
  
  
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  </BODY>
  </HTML>
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text: sv8
  As filed with the U.S. Securities and Exchange Commission on May 15, 2006
  Registration
  No. 333- _________
  UNITED STATES SECURITIES AND EXCHANGE COMMISSION
  Washington, D.C. 20549
  FORM S-8
  REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933
  CABOT CORPORATION
  (Exact name of registrant as specified in its charter)
  Delaware
  (State or other jurisdiction
  of incorporation or organization)
  04-2271897
  (I.R.S. Employer
  Identification No.)
  Two Seaport Lane
  Suite 1300
  Boston, MA
  (Address of principal executive offices)
  02210
  (Zip Code)
  Cabot Corporation 2006 Long-Term Incentive Plan
  Cabot Corporation Non-Employee Directors' Stock Compensation Plan
  (Full title of the plan)
  Brian A. Berube, Esq.
  Vice President and General Counsel
  Two Seaport Lane
  Suite 1300
  Boston, MA 02210
  (Name and address of agent for service)
  617-345-0100
  (Telephone number, including area code, of agent for service)
  CALCULATION OF REGISTRATION FEE
  Proposed Maximum
  Proposed Maximum
  Title Of Securities
  Amount To Be
  Offering Price Per
  Aggregate Offering
  Amount Of
  To Be Registered
  Registered (1)
  Share
  Price
  Registration Fee
  Common Stock,
  Par Value $1.00 per
  share
  4,850,000 shares (2)
  $
  35.235
  (3)
  $
  170,889,750
  (3)
  $18,285.21 (3)
  (1)
  Pursuant to Rule 416(a) under the Securities Act of 1933, this registration statement also
  covers such additional shares of Common Stock as may become issuable under the plans to
  prevent dilution from stock splits, stock dividends and similar transactions.
  (2)
  The shares of Cabot Corporation common stock being registered hereby include (a) 4,500,000
  shares to be offered under the 2006 Long-Term Incentive Plan; and (b) 350,000 shares to be
  offered under the Non-Employee Directors' Stock Compensation Plan.
  (3)
  Estimated solely for the purpose of calculating the registration fee pursuant to Rules 457(c)
  and 457(h) of the Securities Act of 1933, as amended, and based upon the average of the high
  and low prices of the Common Stock as reported on the New York Stock Exchange Composite Tape
  on May 10, 2006.
  PART 1
  INFORMATION REQUIRED IN THE SECTION 10(A) PROSPECTUS
  Item 1. Plan Information.
  The information required by Item 1 will be included in documents sent or given to participants
  in the plan covered by this registration statement pursuant to Rule 428(b)(1) of the Securities Act
  of 1933, as amended (the "Securities Act").
  Item 2. Registrant Information and Employee Plan Annual Information.
  The written statement required by Item 2 will be included in documents sent or given to
  participants in the plan covered by this registration statement pursuant to Rule 428 (b)(1).
  PART II
  INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  Item 3. Incorporation of Documents by Reference.
  The following documents filed with the Securities and Exchange Commission (the "Commission")
  pursuant to the Securities Exchange Act of 1934, as amended (the "Exchange Act") by Cabot
  Corporation (the "Registrant") (Commission File No. 1-5667) are incorporated in this Registration
  Statement by reference and shall be deemed to be a part hereof:
  (a)
  The Registrant's Annual Report on Form 10-K for the fiscal year ended September
  30, 2005, as filed with the Commission on December 14, 2005;
  (b)
  The Registrant's Quarterly Report on Form 10-Q for the quarterly period ended
  December 31, 2005, as filed with the Commission on February 9, 2006;
  (c)
  The Registrant's Quarterly Report on Form 10-Q for the quarterly period ended
  March 31, 2006, as filed with the Commission on May 10, 2006;
  (d)
  The Registrant's Current Reports on Form 8-K as filed with the Commission on
  May 4, 2006, February 9, 2006, February 2, 2006, January 19, 2006, January 10, 2006,
  December 27, 2005, December 13, 2005, November 23, 2005, November 3, 2005, and October
  17, 2005;
  (e)
  The description of the Registrant's Common Stock, $1.00 par value per share,
  contained in the Registrant's Registration Statement on Form 10, filed with the
  Commission pursuant to Section 12 of the Exchange Act.
  All documents subsequently filed by the Registrant pursuant to Sections 13(a), 13(c), 14 and
  15(d) of the Exchange Act, prior to the filing of a post-effective amendment to this Registration
  Statement that indicates that all securities offered have been sold or which deregisters all
  securities then remaining unsold, shall be deemed to be incorporated herein by reference from the
  date of filing of such documents. Any statement contained in this Registration Statement, in an
  amendment hereto or in a document incorporated or deemed to be incorporated by reference herein
  shall be deemed to be modified or superseded for the purposes of this Registration Statement to the
  extent that a statement contained herein or in any other subsequently filed document that also is
  or is deemed to be
  incorporated by reference herein modifies or supersedes such statement. Any statement so
  modified or superseded shall not be deemed, except as so modified or superseded, to constitute a
  part of this Registration Statement.
  Item 4. Description of Securities.
  Not applicable.
  Item 5. Interests of Named Experts and Counsel.
  Brian A. Berube, the Registrant's Vice President and General Counsel, has opined as to the
  legality of the issuance of the Common Stock being registered under this Registration Statement.
  At the time of rendering his opinion, Mr. Berube had a substantial interest in the Registrant, as
  defined by the rules of the Commission, in that the fair market value of the approximately 54,000
  shares of Common Stock owned by him exceeds $50,000. It is anticipated that additional shares will
  be issued to Mr. Berube pursuant to the 2006 Long-Term Incentive Plan and under other employee
  benefit plans of the Registrant.
  Item 6. Indemnification of Directors and Officers.
  Section 145 of the Delaware General Corporation Law, as amended, provides that a corporation
  may
  indemnify any person who was or is a party or is threatened to be made a party to any threatened,
  pending or completed action, suit or proceeding, whether civil, criminal or investigative (other
  than an action by or in the right of the corporation) by reason of the fact that such person is or
  was a director, officer, employee or agent of the corporation, or is or was serving at the request
  of the corporation as director, officer, employee or agent of another corporation, partnership,
  joint venture, trust or other enterprise, against expenses (including attorneys' fees), judgments,
  fines and amounts paid in settlement actually and reasonably incurred by such person in connection
  with such action, suit or proceeding if such person acted in good faith and in a manner such person
  reasonably believed to be in or not opposed to the best interests of the corporation, and, with
  respect to any criminal action or proceeding, had no reasonable cause to believe such person's
  conduct was unlawful. Section 145 further provides that a corporation similarly may indemnify any
  such person serving in any such capacity who was or is a party or is threatened to be made a party
  to any threatened, pending or completed action or suit by or in the right of the corporation to
  procure a judgment in its favor, against expenses actually and reasonably incurred in connection
  with the defense or settlement of such action or suit if such person acted in good faith and in a
  manner such person reasonably believed to be in or not opposed to the best interest of the
  corporation and except that no indemnification shall be made in respect of any claim, issue or
  matter as to which such person shall have been adjudged to be liable to the corporation unless and
  only to the extent that the Delaware Court of Chancery or such other court in which such action or
  suit was brought shall determine upon application that, despite the adjudication of liability but
  in view of all the circumstances of the case, such person is fairly and reasonably entitled to
  indemnity for such expenses which the Court of Chancery or such other court shall deem proper.
  Section 102(b)(7) of the Delaware General Corporation Law, as amended, permits a corporation
  to include in its certificate of incorporation a provision eliminating or limiting the personal
  liability of a director to the corporation or its stockholders for monetary damages for breach of
  fiduciary duty as a director, provided, however, that such provision shall not eliminate or limit
  the liability of a director (i) for any breach of the director's duty of
  loyalty to the corporation
  or its stockholders, (ii) for acts or omissions not in good faith or which involve intentional
  misconduct or a knowing violation of law, (iii) under Section 174 of the Delaware General
  Corporation Law (relating to unlawful payment of dividends and unlawful stock purchase and
  redemption) or (iv) for any transaction from which the director derived an improper personal
  benefit.
  Article Eight (j) of the Registrant's Certificate of Incorporation and Section 14 of the
  Registrant's by-laws provide that the Registrant shall indemnify any person who was a party, is a
  party or is threatened to be made a party to any threatened, pending or completed action, suit, or
  proceeding by reason of the fact that such person is or was a director, officer, employee or agent
  of the Registrant or is or was serving at the request of the Registrant as a director, officer,
  employee or agent of another company or enterprise, including service as a fiduciary of an employee
  benefit plan, against expenses (including attorneys' fees), judgments, fines, penalties and amounts
  paid in settlement incurred in connection with such action, suit or proceeding to the extent
  permitted from time to time under the Delaware General Corporation Law. Such indemnification shall
  be made as authorized in a specific case upon a determination by the Board of Directors or the
  stockholders of the Registrant. The rights of indemnification are not exclusive of any other rights
  to which those seeking indemnification may be entitled and shall continue as to a person who ceases
  to be a director, officer, employee or agent. In addition, under Article Eight (i) of the
  Registrant's Certificate of Incorporation no director or officer of the Registrant shall be liable
  to the Registrant or its stockholders for monetary damages for any breach of fiduciary duty, except
  to the extent that Delaware General Corporation Law prohibits the elimination or limitation of
  liability of directors or officers for breach of fiduciary duty.
  All of the Registrant's directors and officers are covered by insurance policies maintained by
  the Registrant against specified liabilities for actions taken in their capacities as such,
  including liabilities under the Securities Act.
  Item 7. Exemption From Registration Claimed.
  Not applicable.
  Item 8. Exhibits.
  Exhibit
  Number
  Document Description
  4.1
  Restated Certificate of Incorporation of Cabot Corporation (incorporated by
  reference to Exhibit 3.1 to the Quarterly Report on Form 10-Q of Cabot Corporation,
  File No. 1-5667, filed with the Commission on February 9, 2006).
  4.2
  2006 Long-Term Incentive Plan of Cabot Corporation (incorporated by reference
  to Appendix B of Cabot Corporation's Proxy Statement on Schedule 14A relating to the
  2006 Annual Meeting of Shareholders, File No. 1-5667, filed with the Commission on
  January 30, 2006).
  4.3
  Non-Employee Directors' Stock Compensation Plan of Cabot Corporation
  (incorporated by reference to Appendix C of Cabot Corporation's Proxy Statement on
  Schedule 14A relating to the 2006 Annual Meeting of Shareholders, File No. 1-5667,
  filed with the Commission on January 30, 2006).
  5.1*
  Opinion of Brian A. Berube, Vice President and General Counsel.
  23.1*
  Consent of PricewaterhouseCoopers LLP.
  23.2*
  Consent of Brian A. Berube, Vice President and General Counsel (included in Exhibit 5.1).
  24*
  Power of Attorney (included on the signature page of this registration statement).
  *
  Filed herewith
  Item 9. Undertakings.
  (a)
  The undersigned Registrant hereby undertakes:
  (1)
  To file, during any period in which offers or sales are being
  made, a post-effective amendment to this Registration Statement:
  (i)
  To include any prospectus required by Section
  10(a)(3) of the Securities Act;
  (ii)
  To reflect in the prospectus any facts or
  events arising after the effective date of the Registration Statement
  (or the most recent post-effective amendment thereof) which,
  individually or in the aggregate, represent a fundamental change in the
  information set forth in the Registration Statement; and
  (iii)
  To include any material information with
  respect to the plan of distribution not previously disclosed in the
  Registration Statement or any material change to such information in
  the Registration Statement;
  provided, however
  , that paragraphs (a)(1)(i) and (a)(1)(ii) above shall not apply if
  the information required to be included in a post-effective amendment by those
  paragraphs is contained in periodic reports filed with or furnished to the
  Commission by the Registrant pursuant to Section 13 or 15(d) of the Exchange Act
  that are incorporated by reference in the Registration Statement.
  (2)
  That, for the purpose of determining any liability under the
  Securities Act, each such post-effective amendment shall be deemed to be a new
  registration statement relating to the securities offered therein, and the
  offering of such securities at that time shall be deemed to be the initial
  bona
  fide
  offering thereof.
  (3)
  To remove from registration by means of a post-effective
  amendment any of the securities being registered which remain unsold at the
  termination of the offering.
  (b)
  The undersigned Registrant hereby undertakes that, for purposes of determining
  any liability under the Securities Act, each filing of the Registrant's annual report
  pursuant to Section 13(a) or 15(d) of the Exchange Act (and, where applicable, each
  filing of an employee benefit plan's annual report pursuant to Section 15(d) of the
  Exchange Act) that is incorporated by reference in the Registration Statement shall be
  deemed to be a new Registration Statement relating to the securities offered therein,
  and the offering of such securities at that time shall be deemed to be the initial
  bona
  fide
  offering thereof.
  (c)
  Insofar as indemnification for liabilities arising under the Securities Act may
  be permitted to directors, officers and controlling persons of the Registrant pursuant
  to the foregoing provisions,
  or otherwise, the Registrant has been advised that in the opinion of the Commission
  such indemnification is against public policy as expressed in the Securities Act and
  is, therefore, unenforceable. In the event that a claim for indemnification against
  such liabilities (other than the payment by the Registrant of expenses incurred or
  paid by a director, officer or controlling person of the Registrant in the
  successful defense of any action, suit or proceeding) is asserted by such director,
  officer or controlling person in connection with the securities being registered,
  the Registrant will, unless in the opinion of its counsel the matter has been
  settled by controlling precedent, submit to a court of appropriate jurisdiction the
  question whether such indemnification by it is against public policy as expressed in
  the Securities Act and will be governed by the final adjudication of such issue.
  SIGNATURES
  Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it
  has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and
  has duly caused this registration statement to be signed on its behalf by the undersigned,
  thereunto duly authorized, in the City of Boston, The Commonwealth of Massachusetts, on this 12th
  day of May, 2006.
  CABOT CORPORATION
  By:
  /s/ Kennett F. Burnes
  Name:
  Kennett F. Burnes
  Title:
  President and Chief Executive Officer
  SIGNATURES AND POWER OF ATTORNEY
  Each person whose signature appears below constitutes and appoints Brian A. Berube and Jane A.
  Bell and each of them singly, his or her true and lawful attorney-in-fact and agent with full power
  of substitution and resubstitution, for him or her and in his or her name, place and stead as a
  director or officer or both, as the case may be, of Cabot Corporation, to sign any and all
  amendments (including post-effective amendments) to this Registration Statement on Form S-8 to be
  filed by Cabot Corporation, and all documents or instruments necessary or appropriate to enable
  Cabot Corporation to comply with the Securities Act of 1933, as amended, and to file the same, with
  all exhibits thereto, with the Securities and Exchange Commission, granting unto said
  attorneys-in-fact and agents full power and authority to do and perform each and every act
  whatsoever that is necessary, appropriate or advisable in connection with any or all of the
  above-described matters and to all intents and purposes as he or she might or could do in person,
  hereby ratifying and confirming all that said attorneys-in-fact and agents, or their substitutes,
  may lawfully do or cause to be done by virtue hereof.
  * * * *
  Pursuant to the requirements of the Securities Act of 1933, as amended, this registration
  statement has been signed by the following persons in the capacities and on the dates indicated.
  Signature
  Title
  Date
  /s/ Kennett F. Burnes
  Kennett F. Burnes
  Director, Chairman of the Board,
  Chief
  Executive Officer and President
  (Principal Executive Officer)
  May 12, 2006
  /s/ Jonathan P. Mason
  Jonathan P. Mason
  Executive Vice President and Chief
  Financial Officer
  (Principal Financial Officer)
  May 12, 2006
  /s/ James P. Kelly
  James P. Kelly
  Controller
  (Controller/Principal Accounting Officer)
  May 12, 2006
  /s/ John S. Clarkeson
  John S. Clarkeson
  Director
  May 12, 2006
  Signature
  Title
  Date
  /s/ Juan Enriquez-Cabot
  Juan Enriquez-Cabot
  Director
  May 12, 2006
  /s/ Arthur L. Goldstein
  Arthur L. Goldstein
  Director
  May 12, 2006
  /s/ Gautam S. Kaji
  Gautam S. Kaji
  Director
  May 12, 2006
  /s/ Roderick C.G. MacLeod
  Roderick C.G. Macleod
  Director
  May 12, 2006
  /s/ John H. McArthur
  John H. McArthur
  Director
  May 12, 2006
  /s/ Henry F. McCance
  Henry
  F. M
  cCance
  Director
  May 12, 2006
  /s/ John F. O'Brien
  John F. O'Brien
  Director
  May 12, 2006
  /s/ Ronaldo H. Schmitz
  Ronaldo H. Schmitz
  Director
  May 12, 2006
  /s/ Lydia W. Thomas
  Lydia W. Thomas
  Director
  May 12, 2006
  /s/ Mark S. Wrighton
  Mark S. Wrighton
  Director
  May 12, 2006
  /s/ Dirk Blevi
  Dirk Blevi
  Director
  May 12, 2006
  EXHIBIT INDEX
  Exhibit
  Number
  Document Description
  4.1
  Restated Certificate of Incorporation of Cabot Corporation (incorporated by
  reference to Exhibit 3.1 to the Quarterly Report on Form 10-Q of Cabot Corporation,
  File No. 1-5667, filed with the Commission on February 9, 2006).
  4.2
  2006 Long-Term Incentive Plan of Cabot Corporation (incorporated by reference
  to Appendix B of Cabot Corporation's Proxy Statement on Schedule 14A relating to the
  2006 Annual Meeting of Shareholders, File No. 1-5667, filed with the Commission on
  January 30, 2006).
  4.3
  Non-Employee Directors' Stock Compensation Plan of Cabot Corporation
  (incorporated by reference to Appendix C of Cabot Corporation's Proxy Statement on
  Schedule 14A relating to the 2006 Annual Meeting of Shareholders, File No. 1-5667,
  filed with the Commission on January 30, 2006).
  5.1*
  Opinion of Brian A. Berube, Vice President and General Counsel.
  23.1*
  Consent of PricewaterhouseCoopers LLP.
  23.2*
  Consent of Brian A. Berube, Vice President and General Counsel (included in Exhibit 5.1).
  24*
  Power of Attorney (included on the signature page of this registration statement).
  *
  Filed herewith