content: <PAGE>   1
  
  As filed with the Securities and Exchange Commission on March 1, 2000.
  
                                                     Registration No. 333-________
  
  ================================================================================
  
                         SECURITIES AND EXCHANGE COMMISSION
                                WASHINGTON, DC. 20549
  
                                      FORM S-8
  
                            REGISTRATION STATEMENT UNDER
                             THE SECURITIES ACT OF 1933
  
                                  SIPEX Corporation
               (Exact name of registrant as specified in its charter)
  
           Massachusetts                                           04-6135748
  (State or other jurisdiction of                               (I.R.S. Employer
   incorporation or organization)                              Identification No.)
  
                                  22 Linnell Circle
                                 Billerica, MA 01821
                                   (978) 667-8700
                 (Address of Principal Executive Offices) (Zip Code)
  
                            -----------------------------
  
                                   1999 Stock Plan
                              (Full title of the plan)
  
                            -----------------------------
  
                                  James E. Donegan
                               Chief Executive Officer
                                  SIPEX Corporation
                                  22 Linnell Circle
                                 Billerica, MA 01821
                                   (978) 667-8700
             (Name and address including zip code and telephone number,
                     including area code, of agent for service)
  
                            -----------------------------
  
                                     Copies to:
  
                               Kenneth J. Gordon, Esq.
                           TESTA, HURWITZ & THIBEAULT, LLP
                                   125 High Street
                             Boston, Massachusetts 02110
                                   (617) 248-7000
  
  ================================================================================
  
  
  
  <PAGE>   2
  
                                        -2-
  
                           CALCULATION OF REGISTRATION FEE
  
  ================================================================================
  
  <TABLE>
  <CAPTION>
                                                          Proposed
                                                          maximum
                                                          offering         Proposed maximum
       Title of securities               Amount to be     price per           aggragate           Amount of
        to be registered                 registered(1)    share             offering price     registration fee
         ----------------                 ----------      ---------         --------------     ----------------
  
  
  
  1999 STOCK PLAN
  
  <S>                                        <C>          <C>             <C>                   <C>
  Common Stock, par value $.01               270,120      $11.1250(2)     $ 3,005,085.00(2)     $  793.34(2)
  per share
                                               1,625      $ 9.5625(2)     $    15,539.06(2)     $    4.10
  
                                               4,000      $10.4380(2)     $    41,752.00(2)     $   11.02(2)
  
                                              40,950      $12.1250(2)     $   496,518.75(2)     $  131.08(2)
  
                                             265,000      $15.5625(2)     $ 4,124,062.50(2)     $1,088.75(2)
  
                                             225,000      $13.0625(2)     $ 2,939,062.50(2)     $  775.91(2)
  
                                             393,305      $  27.00(3)     $   10,619,235(3)     $2,803.48(3)
  
  NON-PLAN OPTIONS
  
  Common Stock, par value $.01               355,000      $15.5625(2)     $ 5,524,687.50(2)     $1,458.52(2)
  per share
                                              40,000      $ 9.8125(2)     $   392,500.00(2)     $  103.62(2)
  
                                             500,000      $12.5625(2)     $ 6,281,250.00(2)     $1,658.25(2)
  
                                             221,500      $14.8750(2)     $ 3,294,812.50(2)     $  869.83(2)
                                           ---------                      --------------        ---------
  
  TOTAL                                    2,316,500                      $36,734,504.81        $9,697.91
  </TABLE>
  
  ================================================================================
  
  (1)      Plus such additional shares as may be required pursuant to the plan in
           the event of a stock dividend, split-up of shares, recapitalization or
           other similar change in the Common Stock.
  
  (2)      Such shares are issuable upon exercise of outstanding options with
           fixed exercise prices. Pursuant to Rule 457(h)(1) of Regulation C, the
           aggregate offering price and the fee have been computed upon the basis
           of the price at which the options may be exercised. The offering price
           per share set forth for such shares is the exercise price per share at
           which such options are exercisable.
  
  (3)      Pursuant to Rule 457(c) and (h)(1) of Regulation C of the Securities
           Act, the price of $27 per share, is the average of the high and low
           prices of the Common Stock as reported on The Nasdaq National Market on
           February 25, 2000 and is set forth solely for purposes of calculating
           the filing fee for those shares without a fixed exercise price.
  
  
  
  <PAGE>   3
  
                                        -3-
  
           This Registration Statement registers additional securities of the same
  class as other securities for which (i) Registration Statement No. 333-06123 on
  Form S-8 as filed with the Securities and Exchange Commission on June 17, 1996,
  (relating to the Registrant's 1988 Non-Statutory Stock Option Plan, 1991
  Non-Statutory Stock Option Plan, 1993 Stock Option and Incentive Plan, 1994
  Stock Option and Incentive Plan, 1996 Incentive Stock Option Plan, 1996
  Non-Employee Director Stock Option Plan and 1996 Employee Stock Purchase Plan),
  is effective, and (ii) Registration Statement No. 333-32329 on Form S-8 as filed
  with the Securities and Exchange Commission on July 29, 1997 relating to the
  Registrant's 1997 Stock Option Plan is effective. Pursuant to General
  Instruction E to Form S-8, the contents of the above-listed Registration
  Statements are hereby incorporated by reference.
  
  
  <PAGE>   4
  
                                        -4-
  
                                       PART I
  
                INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS
  
  ITEM 1.  PLAN INFORMATION.
  
           The documents containing the information specified in this Item 1 will
  be sent or given to employees, directors or others as specified by Rule
  428(b)(1). In accordance with the rules and regulations of the Securities and
  Exchange Commission (the "Commission") and the instructions to Form S-8, such
  documents are not being filed with the Commission either as part of this
  Registration Statement or as prospectuses or prospectus supplements pursuant to
  Rule 424.
  
  ITEM 2.  REGISTRANT INFORMATION AND EMPLOYEE PLAN ANNUAL INFORMATION.
  
           The documents containing the information specified in this Item 2 will
  be sent or given to employees as specified by Rule 428(b)(1). In accordance with
  the rules and regulations of the Commission and the instructions to Form S-8,
  such documents are not being filed with the Commission either as part of the
  Registration Statement or as prospectuses or prospectus supplements pursuant to
  Rule 424.
  
                                       PART II
  
                 INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  
  ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.
  
           The following documents filed by SIPEX Corporation (the "Registrant")
  with the Commission pursuant to the Securities Exchange Act of 1934, as amended
  (the "Exchange Act"), are incorporated in this Registration Statement by
  reference as of their respective dates:
  
           (a)      The Registrant's Annual Report on Form 10-K for the fiscal
                    year ended December 31, 1998, filed with the Commission on
                    March 31, 1999;
  
           (b)      The Registrant's Quarterly Reports on Form 10-Q for the fiscal
                    quarters ended October 2, 1999 (filed with the Commission on
                    November 16, 1999); July 3, 1999 (filed with the Commission on
                    August 12, 1999); and April 3, 1999 (filed with the Commission
                    on May 14, 1999) under Section 15(d) of the Exchange Act; and
  
           (c)      The section entitled "Description of Registrant's Securities
                    to be Registered" contained in the Registrant's registration
                    statement on Form 8-A filed with the Commission pursuant to
                    Section 12(g) of the Exchange Act and incorporating by
                    reference the information contained in the Registrant's
                    Registration Statement on Form S-1 (SEC File No. 333-1328).
  
           All documents subsequently filed with the Commission 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 which indicates that all securities
  offered herein have been sold or which deregisters all securities then remaining
  unsold, shall be deemed to be incorporated by reference in this Registration
  Statement and to be a part hereof from the date of filing of such documents.
  
  ITEM 4. DESCRIPTION OF SECURITIES.
  
  Not applicable.
  
  
  <PAGE>   5
  
                                        -5-
  
  
  ITEM 5. INTEREST OF NAMED EXPERTS AND COUNSEL
  
  Not applicable.
  
  ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS.
  
  Massachusetts General Laws Chapter 156B, Section 67 provides that a corporation
  may indemnify its directors and officers to the extent specified in or
  authorized by (i) the articles of organization, (ii) a by-law adopted by the
  shareholders, or (iii) a vote adopted by the holders of a majority of the shares
  of stock entitled to vote on the election of directors. In all instances, the
  extent to which a corporation provides indemnification to its directors and
  officers under Section 67 is optional. Massachusetts General Laws Chapter 156B,
  Section 67 forbids the indemnification of any person with respect to any matter
  to which he shall have been adjudicated in any proceeding not to have acted in
  good faith in the reasonable belief that his action was in the best interest of
  the corporation.
  
  The Company's Restated By-Laws indemnifies the directors and officers against
  liabilities arising out of legal proceedings brought against them by reason of
  their status as directors and officers or by reason of their agreeing to serve,
  at the request of the Company, as a director or officer of another organization.
  Under the Restated By-Laws, each director and officer shall be indemnified by
  the Company for all costs and expenses (including attorneys' fees), judgments,
  liabilities and amounts paid in settlement of such proceedings, even if he is
  not successful on the merits, if he acted in good faith in the reasonable belief
  that his action was in the best interest of the Company. The Board of Directors
  may authorize advancing litigation expenses to a director or officer at his
  request upon receipt of an undertaking by such director or officer to repay such
  expenses if it is ultimately determined that he is not entitled to
  indemnification for such expense. The Restated By-Laws provide that the
  directors and officers of the Company shall be indemnified by the Company to the
  fullest extent authorized by Massachusetts Law, as it now exists or may in the
  future be amended. In addition, the Restated Articles provide that the directors
  of the Company will not be personally liable for monetary damages to the Company
  for breaches of their fiduciary duty as directors, unless they violated their
  duty of loyalty to the Company or its shareholders, acted in bad faith,
  knowingly or intentionally violated the law, authorized illegal dividends or
  redemptions or derived an improper personal benefit from their action as
  directors.
  
  The Company has entered into separate indemnification agreements with each of
  its directors and executive officers, whereby the Company agreed, among other
  things, (i) to indemnify them to the fullest extent permitted by the Business
  Corporation Law of the Commonwealth of Massachusetts, subject to specified
  limitations, against certain liabilities actually and reasonably incurred by
  them in any proceedings in which they are a party that may arise by reason of
  their status as directors, officers, employees or agents or may arise by reason
  of their serving as such at the request of the Company for another entity and
  (ii) to advance their expenses incurred as a result of any proceeding against
  them as to which they could be indemnified. The Company intends to enter into
  similar separate indemnification agreements with any directors or officers who
  may join the Company in the future.
  
   ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.
  
   Not applicable.
  
  ITEM 8.  EXHIBITS.
  
                    EXHIBIT NO.                    DESCRIPTION OF EXHIBIT
  
                           4.1            Restated Articles of Organization of the
                                          Registrant (filed as Exhibit 3.2 to the
                                          Registrant's Registration Statement on
                                          Form S-1, File No. 333-1328, and
                                          incorporated herein by reference).
  
  
  <PAGE>   6
  
                                        -6-
  
  
                           4.2            Restated By-Laws of the Registrant
                                          (filed as Exhibit 3.3 to the
                                          Registrant's Registration Statement on
                                          Form S-1, File No. 333-1328, and
                                          incorporated herein by reference).
  
                           4.3            SIPEX Corporation 1999 Stock Plan.
  
                           4.4            Non-Qualified Stock Option Agreement
                                          dated August 12, 1999 by and between the
                                          Registrant and Stephen E. Parks.
  
                           4.5            Non-Qualified Stock Option Agreement
                                          dated November 23, 1999 by and between
                                          the Registrant and Manuel DelArroz
  
                           4.6            Form of Standard Employee Non-Qualified
                                          Option Agreement
  
                           5.1            Opinion of Testa, Hurwitz & Thibeault,
                                          LLP.
  
                          23.1            Consent of Testa, Hurwitz & Thibeault,
                                          LLP (contained in its opinion as Exhibit
                                          5.1).
  
                          23.2            Consent of KPMG LLP.
  
                          24.1            Power of Attorney (included as part of
                                          the signature page of this Registration
                                          Statement).
  
  
  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 of
                                      1933;
  
                             (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) do 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 Section 15(d) of the
                             Securities Exchange Act of 1934 that are incorporated
                             by reference in the Registration Statement.
  
  
  <PAGE>   7
  
                                        -7-
  
                    (2)      That, for the purpose of determining any liability
                             under the Securities Act of 1933, 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
                    of 1933, each filing of the Registrant's annual report
                    pursuant to Section 13(a) or Section 15(d) of the Securities
                    Exchange Act of 1934 (and, where applicable, each filing of
                    any employee benefit plan's annual report pursuant to Section
                    15(d) of the Securities Exchange Act of 1934) 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 of 1933 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 Securities and Exchange
                    Commission such indemnification is against public policy as
                    expressed in the 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 Act and will be
                    governed by the final adjudication of such issue.
  
  
  
  
  <PAGE>   8
  \
  
                                        -8-
  
  
                                     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 Billerica, the Commonwealth of Massachusetts, on this
  9th day of February, 2000.
  
  
                                 SIPEX CORPORATION
  
                                 By:  /s/ James E. Donegan
                                      ------------------------------------
                                      James E. Donegan
                                      Chairman of the Board of Directors and Chief
                                      Executive Officer
  
  
                                  POWER OF ATTORNEY
  
           EACH SUCH PERSON WHOSE SIGNATURE appears below constitutes and
  appoints, jointly and severally, James E. Donegan and Frank R. DiPietro and each
  of them, with full power to act without the other, his true and lawful
  attorney-in-fact and agent, with the power of substitution and resubstitution,
  for him and in his name, place and stead, in any and all capacities, to sign any
  amendments to this Registration Statement on Form S-8 (including post-effective
  amendments) and to file the same, with all exhibits thereto, and other documents
  in connection therewith, with the Securities and Exchange Commission, hereby
  ratifying and confirming all that said attorney-in-fact, or his or her
  substitute or substitutes, may do or cause to be done by virtue hereof.
  
           Pursuant to the requirements of the Securities Act of 1933, this
  Registration Statement has been signed by the following persons in the
  capacities and on the date indicated.
  
             SIGNATURE                          TITLE                     DATE
  
  /s/ James E. Donegan
  -------------------------------    Chairman of the Board of
    James E. Donegan                 Directors, Chief Executive
                                     Officer and Director
  
  /s/ Frank R. DiPietro
  -------------------------------    Executive Vice President,
    Frank R. DiPietro                Finance, Chief Financial
                                     Officer, Treasurer
                                     (principal financial officer
                                     and accounting officer) and
                                     Clerk
  
  /s/ Manfred Loeb
  -------------------------------    Director
    Manfred Loeb
  
  /s/ Lionel H. Olmer
  -------------------------------    Director
    Lionel H. Olmer
  
  /s/ John L. Sprague
  -------------------------------    Director
    John L. Sprague
  
  /s/ Steward Flaschen
  -------------------------------    Director
    Dr. Steward S. Flaschen
  
  /s/ Willy Sansen
  -------------------------------    Director
    Willy Sansen
  
  
  
  <PAGE>   9
  
                                        -9-
  
  
                                  INDEX TO EXHIBITS
  
  
        EXHIBIT                     DESCRIPTION OF EXHIBIT
  
          4.1*          Restated Articles of Organization of the
                        Registrant.
  
          4.2*          Restated By-Laws of the Registrant.
  
          4.3**         SIPEX Corporation 1999 Stock Plan.
  
          4.4           Non-Qualified Option Agreement dated August 12, 1999
                        between the Registrant and Stephen E.
                        Parks.
  
          4.5           Non-Qualified Stock Option Agreement dated
                        November 23, 1999 by and between the
                         Registrant and Manuel DelArroz
  
          4.6           Form of Standard Employee Non-Qualified Option
                        Agreement
  
          5.1           Opinion of Testa, Hurwitz & Thibeault, LLP.
  
          23.1          Consent of Testa, Hurwitz & Thibeault, LLP (contained in
                        its opinion as Exhibit 5.1).
  
          23.2          Consent of  KPMG LLP.
  
          24.1          Power of Attorney (contained on page 8 of this
                        Registration Statement on Form S-8).
  
  
  * Incorporated by reference to Exhibits to the Registrant's Registration
    Statement on Form S-1, No. 333-1328
  
  ** Incorporated by reference to the Registrant's 1998 Proxy Statement on
     Schedule 14A, No. 1000-27892
metadata_documents: [{"type": "S-8", "sequence": "1", "description": "SIPEX CORPORATION", "secsgml_size_bytes": 25153}]
metadata_filer: {"company-data": {"conformed-name": "SIPEX CORP", "cik": "0001007800", "assigned-sic": "3674", "irs-number": "046135748", "state-of-incorporation": "MA", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-31410", "film-number": "558884"}, "business-address": {"street1": "22 LINNELL CIRCLE", "city": "BILLERICA", "state": "MA", "zip": "01821", "phone": "9786678700"}, "mail-address": {"street1": "22 LINNELL CIRCLE", "city": "BILLERICA", "state": "MA", "zip": "01821"}}
text: 1
  
  As filed with the Securities and Exchange Commission on March 1, 2000.
  
                                                     Registration No. 333-________
  
  ================================================================================
  
                         SECURITIES AND EXCHANGE COMMISSION
                                WASHINGTON, DC. 20549
  
                                      FORM S-8
  
                            REGISTRATION STATEMENT UNDER
                             THE SECURITIES ACT OF 1933
  
                                  SIPEX Corporation
               (Exact name of registrant as specified in its charter)
  
           Massachusetts                                           04-6135748
  (State or other jurisdiction of                               (I.R.S. Employer
   incorporation or organization)                              Identification No.)
  
                                  22 Linnell Circle
                                 Billerica, MA 01821
                                   (978) 667-8700
                 (Address of Principal Executive Offices) (Zip Code)
  
                            -----------------------------
  
                                   1999 Stock Plan
                              (Full title of the plan)
  
                            -----------------------------
  
                                  James E. Donegan
                               Chief Executive Officer
                                  SIPEX Corporation
                                  22 Linnell Circle
                                 Billerica, MA 01821
                                   (978) 667-8700
             (Name and address including zip code and telephone number,
                     including area code, of agent for service)
  
                            -----------------------------
  
                                     Copies to:
  
                               Kenneth J. Gordon, Esq.
                           TESTA, HURWITZ & THIBEAULT, LLP
                                   125 High Street
                             Boston, Massachusetts 02110
                                   (617) 248-7000
  
  ================================================================================
  2
  
                                        -2-
  
                           CALCULATION OF REGISTRATION FEE
  
  ================================================================================
  Proposed
                                                          maximum
                                                          offering         Proposed maximum
       Title of securities               Amount to be     price per           aggragate           Amount of
        to be registered                 registered(1)    share             offering price     registration fee
         ----------------                 ----------      ---------         --------------     ----------------
  
  1999 STOCK PLAN
  Common Stock, par value $.01               270,120      $11.1250(2)     $ 3,005,085.00(2)     $  793.34(2)
  per share
                                               1,625      $ 9.5625(2)     $    15,539.06(2)     $    4.10
  
                                               4,000      $10.4380(2)     $    41,752.00(2)     $   11.02(2)
  
                                              40,950      $12.1250(2)     $   496,518.75(2)     $  131.08(2)
  
                                             265,000      $15.5625(2)     $ 4,124,062.50(2)     $1,088.75(2)
  
                                             225,000      $13.0625(2)     $ 2,939,062.50(2)     $  775.91(2)
  
                                             393,305      $  27.00(3)     $   10,619,235(3)     $2,803.48(3)
  
  NON-PLAN OPTIONS
  
  Common Stock, par value $.01               355,000      $15.5625(2)     $ 5,524,687.50(2)     $1,458.52(2)
  per share
                                              40,000      $ 9.8125(2)     $   392,500.00(2)     $  103.62(2)
  
                                             500,000      $12.5625(2)     $ 6,281,250.00(2)     $1,658.25(2)
  
                                             221,500      $14.8750(2)     $ 3,294,812.50(2)     $  869.83(2)
                                           ---------                      --------------        ---------
  
  TOTAL                                    2,316,500                      $36,734,504.81        $9,697.91
  ================================================================================
  
  (1)      Plus such additional shares as may be required pursuant to the plan in
           the event of a stock dividend, split-up of shares, recapitalization or
           other similar change in the Common Stock.
  
  (2)      Such shares are issuable upon exercise of outstanding options with
           fixed exercise prices. Pursuant to Rule 457(h)(1) of Regulation C, the
           aggregate offering price and the fee have been computed upon the basis
           of the price at which the options may be exercised. The offering price
           per share set forth for such shares is the exercise price per share at
           which such options are exercisable.
  
  (3)      Pursuant to Rule 457(c) and (h)(1) of Regulation C of the Securities
           Act, the price of $27 per share, is the average of the high and low
           prices of the Common Stock as reported on The Nasdaq National Market on
           February 25, 2000 and is set forth solely for purposes of calculating
           the filing fee for those shares without a fixed exercise price.
  3
  
                                        -3-
  
           This Registration Statement registers additional securities of the same
  class as other securities for which (i) Registration Statement No. 333-06123 on
  Form S-8 as filed with the Securities and Exchange Commission on June 17, 1996,
  (relating to the Registrant's 1988 Non-Statutory Stock Option Plan, 1991
  Non-Statutory Stock Option Plan, 1993 Stock Option and Incentive Plan, 1994
  Stock Option and Incentive Plan, 1996 Incentive Stock Option Plan, 1996
  Non-Employee Director Stock Option Plan and 1996 Employee Stock Purchase Plan),
  is effective, and (ii) Registration Statement No. 333-32329 on Form S-8 as filed
  with the Securities and Exchange Commission on July 29, 1997 relating to the
  Registrant's 1997 Stock Option Plan is effective. Pursuant to General
  Instruction E to Form S-8, the contents of the above-listed Registration
  Statements are hereby incorporated by reference.
  4
  
                                        -4-
  
                                       PART I
  
                INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS
  
  ITEM 1.  PLAN INFORMATION.
  
           The documents containing the information specified in this Item 1 will
  be sent or given to employees, directors or others as specified by Rule
  428(b)(1). In accordance with the rules and regulations of the Securities and
  Exchange Commission (the "Commission") and the instructions to Form S-8, such
  documents are not being filed with the Commission either as part of this
  Registration Statement or as prospectuses or prospectus supplements pursuant to
  Rule 424.
  
  ITEM 2.  REGISTRANT INFORMATION AND EMPLOYEE PLAN ANNUAL INFORMATION.
  
           The documents containing the information specified in this Item 2 will
  be sent or given to employees as specified by Rule 428(b)(1). In accordance with
  the rules and regulations of the Commission and the instructions to Form S-8,
  such documents are not being filed with the Commission either as part of the
  Registration Statement or as prospectuses or prospectus supplements pursuant to
  Rule 424.
  
                                       PART II
  
                 INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  
  ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.
  
           The following documents filed by SIPEX Corporation (the "Registrant")
  with the Commission pursuant to the Securities Exchange Act of 1934, as amended
  (the "Exchange Act"), are incorporated in this Registration Statement by
  reference as of their respective dates:
  
           (a)      The Registrant's Annual Report on Form 10-K for the fiscal
                    year ended December 31, 1998, filed with the Commission on
                    March 31, 1999;
  
           (b)      The Registrant's Quarterly Reports on Form 10-Q for the fiscal
                    quarters ended October 2, 1999 (filed with the Commission on
                    November 16, 1999); July 3, 1999 (filed with the Commission on
                    August 12, 1999); and April 3, 1999 (filed with the Commission
                    on May 14, 1999) under Section 15(d) of the Exchange Act; and
  
           (c)      The section entitled "Description of Registrant's Securities
                    to be Registered" contained in the Registrant's registration
                    statement on Form 8-A filed with the Commission pursuant to
                    Section 12(g) of the Exchange Act and incorporating by
                    reference the information contained in the Registrant's
                    Registration Statement on Form S-1 (SEC File No. 333-1328).
  
           All documents subsequently filed with the Commission 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 which indicates that all securities
  offered herein have been sold or which deregisters all securities then remaining
  unsold, shall be deemed to be incorporated by reference in this Registration
  Statement and to be a part hereof from the date of filing of such documents.
  
  ITEM 4. DESCRIPTION OF SECURITIES.
  
  Not applicable.
  5
  
                                        -5-
  
  ITEM 5. INTEREST OF NAMED EXPERTS AND COUNSEL
  
  Not applicable.
  
  ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS.
  
  Massachusetts General Laws Chapter 156B, Section 67 provides that a corporation
  may indemnify its directors and officers to the extent specified in or
  authorized by (i) the articles of organization, (ii) a by-law adopted by the
  shareholders, or (iii) a vote adopted by the holders of a majority of the shares
  of stock entitled to vote on the election of directors. In all instances, the
  extent to which a corporation provides indemnification to its directors and
  officers under Section 67 is optional. Massachusetts General Laws Chapter 156B,
  Section 67 forbids the indemnification of any person with respect to any matter
  to which he shall have been adjudicated in any proceeding not to have acted in
  good faith in the reasonable belief that his action was in the best interest of
  the corporation.
  
  The Company's Restated By-Laws indemnifies the directors and officers against
  liabilities arising out of legal proceedings brought against them by reason of
  their status as directors and officers or by reason of their agreeing to serve,
  at the request of the Company, as a director or officer of another organization.
  Under the Restated By-Laws, each director and officer shall be indemnified by
  the Company for all costs and expenses (including attorneys' fees), judgments,
  liabilities and amounts paid in settlement of such proceedings, even if he is
  not successful on the merits, if he acted in good faith in the reasonable belief
  that his action was in the best interest of the Company. The Board of Directors
  may authorize advancing litigation expenses to a director or officer at his
  request upon receipt of an undertaking by such director or officer to repay such
  expenses if it is ultimately determined that he is not entitled to
  indemnification for such expense. The Restated By-Laws provide that the
  directors and officers of the Company shall be indemnified by the Company to the
  fullest extent authorized by Massachusetts Law, as it now exists or may in the
  future be amended. In addition, the Restated Articles provide that the directors
  of the Company will not be personally liable for monetary damages to the Company
  for breaches of their fiduciary duty as directors, unless they violated their
  duty of loyalty to the Company or its shareholders, acted in bad faith,
  knowingly or intentionally violated the law, authorized illegal dividends or
  redemptions or derived an improper personal benefit from their action as
  directors.
  
  The Company has entered into separate indemnification agreements with each of
  its directors and executive officers, whereby the Company agreed, among other
  things, (i) to indemnify them to the fullest extent permitted by the Business
  Corporation Law of the Commonwealth of Massachusetts, subject to specified
  limitations, against certain liabilities actually and reasonably incurred by
  them in any proceedings in which they are a party that may arise by reason of
  their status as directors, officers, employees or agents or may arise by reason
  of their serving as such at the request of the Company for another entity and
  (ii) to advance their expenses incurred as a result of any proceeding against
  them as to which they could be indemnified. The Company intends to enter into
  similar separate indemnification agreements with any directors or officers who
  may join the Company in the future.
  
   ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.
  
   Not applicable.
  
  ITEM 8.  EXHIBITS.
  
                    EXHIBIT NO.                    DESCRIPTION OF EXHIBIT
  
                           4.1            Restated Articles of Organization of the
                                          Registrant (filed as Exhibit 3.2 to the
                                          Registrant's Registration Statement on
                                          Form S-1, File No. 333-1328, and
                                          incorporated herein by reference).
  6
  
                                        -6-
  
                           4.2            Restated By-Laws of the Registrant
                                          (filed as Exhibit 3.3 to the
                                          Registrant's Registration Statement on
                                          Form S-1, File No. 333-1328, and
                                          incorporated herein by reference).
  
                           4.3            SIPEX Corporation 1999 Stock Plan.
  
                           4.4            Non-Qualified Stock Option Agreement
                                          dated August 12, 1999 by and between the
                                          Registrant and Stephen E. Parks.
  
                           4.5            Non-Qualified Stock Option Agreement
                                          dated November 23, 1999 by and between
                                          the Registrant and Manuel DelArroz
  
                           4.6            Form of Standard Employee Non-Qualified
                                          Option Agreement
  
                           5.1            Opinion of Testa, Hurwitz & Thibeault,
                                          LLP.
  
                          23.1            Consent of Testa, Hurwitz & Thibeault,
                                          LLP (contained in its opinion as Exhibit
                                          5.1).
  
                          23.2            Consent of KPMG LLP.
  
                          24.1            Power of Attorney (included as part of
                                          the signature page of this Registration
                                          Statement).
  
  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 of
                                      1933;
  
                             (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) do 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 Section 15(d) of the
                             Securities Exchange Act of 1934 that are incorporated
                             by reference in the Registration Statement.
  7
  
                                        -7-
  
                    (2)      That, for the purpose of determining any liability
                             under the Securities Act of 1933, 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
                    of 1933, each filing of the Registrant's annual report
                    pursuant to Section 13(a) or Section 15(d) of the Securities
                    Exchange Act of 1934 (and, where applicable, each filing of
                    any employee benefit plan's annual report pursuant to Section
                    15(d) of the Securities Exchange Act of 1934) 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 of 1933 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 Securities and Exchange
                    Commission such indemnification is against public policy as
                    expressed in the 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 Act and will be
                    governed by the final adjudication of such issue.
  8
  \
  
                                        -8-
  
                                     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 Billerica, the Commonwealth of Massachusetts, on this
  9th day of February, 2000.
  
                                 SIPEX CORPORATION
  
                                 By:  /s/ James E. Donegan
                                      ------------------------------------
                                      James E. Donegan
                                      Chairman of the Board of Directors and Chief
                                      Executive Officer
  
                                  POWER OF ATTORNEY
  
           EACH SUCH PERSON WHOSE SIGNATURE appears below constitutes and
  appoints, jointly and severally, James E. Donegan and Frank R. DiPietro and each
  of them, with full power to act without the other, his true and lawful
  attorney-in-fact and agent, with the power of substitution and resubstitution,
  for him and in his name, place and stead, in any and all capacities, to sign any
  amendments to this Registration Statement on Form S-8 (including post-effective
  amendments) and to file the same, with all exhibits thereto, and other documents
  in connection therewith, with the Securities and Exchange Commission, hereby
  ratifying and confirming all that said attorney-in-fact, or his or her
  substitute or substitutes, may do or cause to be done by virtue hereof.
  
           Pursuant to the requirements of the Securities Act of 1933, this
  Registration Statement has been signed by the following persons in the
  capacities and on the date indicated.
  
             SIGNATURE                          TITLE                     DATE
  
  /s/ James E. Donegan
  -------------------------------    Chairman of the Board of
    James E. Donegan                 Directors, Chief Executive
                                     Officer and Director
  
  /s/ Frank R. DiPietro
  -------------------------------    Executive Vice President,
    Frank R. DiPietro                Finance, Chief Financial
                                     Officer, Treasurer
                                     (principal financial officer
                                     and accounting officer) and
                                     Clerk
  
  /s/ Manfred Loeb
  -------------------------------    Director
    Manfred Loeb
  
  /s/ Lionel H. Olmer
  -------------------------------    Director
    Lionel H. Olmer
  
  /s/ John L. Sprague
  -------------------------------    Director
    John L. Sprague
  
  /s/ Steward Flaschen
  -------------------------------    Director
    Dr. Steward S. Flaschen
  
  /s/ Willy Sansen
  -------------------------------    Director
    Willy Sansen
  9
  
                                        -9-
  
                                  INDEX TO EXHIBITS
  
        EXHIBIT                     DESCRIPTION OF EXHIBIT
  
          4.1*          Restated Articles of Organization of the
                        Registrant.
  
          4.2*          Restated By-Laws of the Registrant.
  
          4.3**         SIPEX Corporation 1999 Stock Plan.
  
          4.4           Non-Qualified Option Agreement dated August 12, 1999
                        between the Registrant and Stephen E.
                        Parks.
  
          4.5           Non-Qualified Stock Option Agreement dated
                        November 23, 1999 by and between the
                         Registrant and Manuel DelArroz
  
          4.6           Form of Standard Employee Non-Qualified Option
                        Agreement
  
          5.1           Opinion of Testa, Hurwitz & Thibeault, LLP.
  
          23.1          Consent of Testa, Hurwitz & Thibeault, LLP (contained in
                        its opinion as Exhibit 5.1).
  
          23.2          Consent of  KPMG LLP.
  
          24.1          Power of Attorney (contained on page 8 of this
                        Registration Statement on Form S-8).
  
  * Incorporated by reference to Exhibits to the Registrant's Registration
    Statement on Form S-1, No. 333-1328
  
  ** Incorporated by reference to the Registrant's 1998 Proxy Statement on
     Schedule 14A, No. 1000-27892