content: <PAGE>   1
      As filed with the Securities and Exchange Commission on June 17, 1996.
                                                        Registration No. 333-
  
  ==============================================================================
  
                         SECURITIES AND EXCHANGE COMMISSION
                               WASHINGTON, D.C. 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 Identification No.)
  incorporation or organization) 
  
                                  22 Linnell Circle
                           Billerica, Massachusetts 01821
                                  (508) 667-8700
                 (Address of Principal Executive Offices) (Zip Code)
  
                               ----------------------
  
                        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
                          1996 Employee Stock Purchase Plan
                              (Full title of the plans)
  
                               ----------------------
  
                                  James E. Donegan
                        President and Chief Executive Officer
                                  SIPEX Corporation
                                  22 Linnell Circle
                           Billerica, Massachusetts 01821
                                  (508) 667-8700
             (Name and address including zip code and telephone number,
                     including area code, of agent for service)
  
                               ----------------------
  
                                      Copy to:
  
                              Timothy C. Maguire, Esq.
                           TESTA, HURWITZ & THIBEAULT, LLP
                         High Street Tower, 125 High Street
                             Boston, Massachusetts 02110
                                   (617) 248-7000
  
     Approximate date of commencement of proposed sale to the public: As soon as
  practicable after this Registration Statement becomes effective.
  
                               ----------------------
  
  
  
  ==============================================================================
  
  
  
  <PAGE>   2
  <TABLE>
  
                           CALCULATION OF REGISTRATION FEE
  <CAPTION>
  
  =================================================================================
  
                                            Proposed      Proposed
                                             Maximum      Maximum
           Title of              Amount     Offering     Aggregate    Amount of
         Securities to           to be      Price Per     Offering    Registration
         be Registered         Registered     Share        Price         Fee
  - ---------------------------------------------------------------------------------
  
  <S>                            <C>         <C>         <C>            <C>      
  1988 NON-STATUTORY STOCK
  OPTION PLAN
  Common Stock (Par Value $.01)        500   $11.00(1)   $     5,500    $    1.90
  
  1991 NON-STATUTORY STOCK
  OPTION PLAN
  Common Stock (Par Value $.01)    211,654   $ 0.40(1)   $    84,662    $   29.19
  
  1993 STOCK OPTION AND
  INCENTIVE PLAN
  Common Stock (Par Value $.01)     91,250   $ 0.40(1)   $    36,500    $   12.59
  
  1994 STOCK OPTION AND
  INCENTIVE PLAN
  Common Stock (Par Value $.01)    444,913   $ 0.40(1)   $   177,965    $   61.37
  
  1996 INCENTIVE STOCK
  OPTION PLAN
  Common Stock (Par Value $.01)    600,000   $18.19(2)   $10,914,000    $3,763.45
  
  1996 NON-EMPLOYEE
  DIRECTOR STOCK OPTION PLAN
  Common Stock                      50,000   $ 9.50(1)   $   475,000    $  163.79
  (Par Value $.01)                 100,000   $18.19(2)   $ 1,819,000    $  627.24
  
  1996 EMPLOYEE STOCK PURCHASE 
  PLAN
  
  Common Stock (Par Value $.01)    250,000   $18.19(2)   $ 4,547,500    $1,568.10
  
  TOTAL:                         1,748,317                              $6,227.63
  
  
  
  - ---------------------------------------------------------------------------------
  <FN>
  
  (1) All such shares are issuable upon exercise of outstanding options with fixed
      exercise prices. Pursuant to Regulation C, Rule 457(h)(1) under the
      Securities Act of 1933, as amended, the aggregate offering price and the fee
      have been computed upon the basis of the price at which the options may be
      exercised.
  
  (2) The price of $18.19 per share, which is the average of the high and low
      prices of the common stock of the registrant reported on the Nasdaq National
      Market on June 12, 1996, is set forth solely for purposes of calculating the
      filing fee pursuant to Rule 457(c) and (h) and has been used only for those
      shares without a fixed exercise price.
  
  </TABLE>
  
  
  <PAGE>   3
  
                                       -3-
  
  
                                       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 this
  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 with the Commission are incorporated by
  reference in this Registration Statement:
  
        (a)   Registrant's Prospectus dated April 2, 1996 as filed with the
              Commission pursuant to Rule 424(b)(1) of the Securities Act of 1933,
              as amended (the "Securities Act"), on April 3, 1996; and
  
        (b)   The section entitled "Description of Registrant's Securities to be
              Registered," contained in the Registrant's Registration Statement on
              Form 8-A, filed on March 1, 1996 pursuant to Section 12(g) of the
              Securities Exchange Act of 1934, as amended (the "Exchange Act").
  
        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.
  
  <PAGE>   4
                                        -4-
  
  
  Item 4. Description of Securities.
          --------------------------
  
        Not applicable.
  
  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.
  
  
  
  
  
  <PAGE>   5
  
  
                                        -5-
  
  
  
  Item 7. Exemption From Registration Claimed.
          ------------------------------------
  
        Not applicable.
  
  Item 8. Exhibits.
          ---------
   
        Exhibit No.       Description of Exhibit
        ----------        ----------------------
  
        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).
  
        Exhibit 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).
  
        Exhibit 4.3       Specimen certificate representing the Common Stock
                          of the Registrant (filed as Exhibit 4.1 to the
                          Registrant's Registration Statement on Form S-1, File
                          No. 333-1328, and incorporated herein by reference).
  
        Exhibit 4.4       1988 Non-Statutory Stock Option Plan (filed as
                          Exhibit 10.1 to the Registrant's Registration Statement
                          on Form S-1, File No. 333-1328, and incorporated herein
                          by reference).
  
        Exhibit 4.5       1991 Non-Statutory Stock Option Plan (filed as
                          Exhibit 10.2 to the Registrant's Registration Statement
                          on Form S-1, File No. 333-1328, and incorporated herein
                          by reference).
  
        ExhibiT 4.6       1993 Stock Option and Incentive Plan (filed as
                          Exhibit 10.3 to the Registrant's Registration Statement
                          on Form S-1, File No. 333-1328, and incorporated herein
                          by reference).
  
        Exhibit 4.7       1994 Stock Option and Incentive Plan (filed as
                          Exhibit 10.4 to the Registrant's Registration Statement
                          on Form S-1, File No. 333-1328, and incorporated herein
                          by reference).
  
        Exhibit 4.8       1996 Incentive Stock Option Plan (filed as Exhibit
                          10.5 to the Registrant's Registration Statement on Form
                          S-1, File No. 333-1328, and incorporated herein by
                          reference).
  
        Exhibit 4.9       1996 Non-Employee Director Stock Option Plan (filed
                          as Exhibit 10.6 to the Registrant's Registration
                          Statement on Form S-1, File No. 333-1328, and
                          incorporated herein by reference).
  
  
  
  
  <PAGE>   6
                                        -6-
  
  
        Exhibit 4.10      1996 Employee Stock Purchase Plan (filed as Exhibit
                          10.7 to the Registrant's Registration Statement on Form
                          S-1, File No. 333-1328, and incorporated herein by
                          reference).
  
        Exhibit 5.1       Opinion of Testa, Hurwitz & Thibeault, LLP (filed
                          herewith).
  
        Exhibit 23.1      Consent of Testa, Hurwitz & Thibeault, LLP (contained in
                          Exhibit 5.1).
  
        Exhibit 23.2      Consent of KPMG Peat Marwick LLP (filed herewith).
  
        Exhibit 23.3      Consent of Ernst & Young LLP (filed herewith).
  
        Exhibit 24.1      Power of Attorney (included as part of the signature 
                          page to 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;
  
                    (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.
  
              (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, 
  
  
  
  <PAGE>   7
                                        -7-
  
  
  
  
                    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 an 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 Securities Act of 1933 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.
  
  
                        [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]
  
  
  <PAGE>   8
                                        -8-
  
  
  
  
                                     SIGNATURES
  
  
        Pursuant to the requirements of the Securities Act of 1933, the
  Registrant, SIPEX Corporation, 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 Town of Billerica, Commonwealth
  of Massachusetts, on this 17th day of June, 1996.
  
  
  
                                      SIPEX Corporation
  
  
                                      By:   /s/ James E. Donegan
                                            -----------------------------------
                                            James E. Donegan
                                            Chairman, Chief Executive Officer,
                                            President and Clerk
  
  
  
                                  POWER OF ATTORNEY
  
        We, the undersigned officers and directors of SIPEX Corporation hereby
  severally constitute and appoint James E. Donegan and Frank R. DiPietro, and
  each of them singly, our true and lawful attorneys, with full power to them and
  each of them singly, to sign for us in our names in the capacities indicated
  below, 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, and generally to do all things in our names and on our behalf in our
  capacities as officers and directors to enable SIPEX Corporation to comply with
  the provisions of the Securities Act of 1933, as amended, hereby ratifying and
  confirming our signatures as they may be signed by our said attorneys, or any of
  them, to said Registration Statement and all amendments thereto.
  
        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 dates indicated.
  
           SIGNATURE                     TITLE(S)                    DATE
           ---------                     --------                    ----
  
    /s/  James E. Donegan            President, Chief             June 17, 1996
   ----------------------------      Executive Officer
    James E. Donegan                 (Principal Executive
                                     Officer) and Clerk
                                    
  
  
  
  
  
  <PAGE>   9
  
                                        -9-
  
  
  
             SIGNATURE                     TITLE(S)                   DATE
             ---------                     --------                   ----
  
   /s/ Frank R. DiPietro              Senior Vice President,       June 17, 1996
  - -------------------------------     Chief Financial
   Frank R. DiPietro                  Officer and
                                      Treasurer (Principal
                                      Financial Officer
                                      and Principal
                                      Accounting Officer)
  
  
   /s/  Daniel Deroux                 Director                     June 17, 1996
  - -------------------------------
   Daniel Deroux
  
  
   /s/  Manfred Loeb                  Director                     June 17, 1996
  - -------------------------------
    Manfred Loeb
  
  
   /s/  Lionel H. Olmer               Director                     June 17, 1996
  - -------------------------------
   Lionel H. Olmer
  
                                                      
   /s/ John L. Sprague                Director                     June 17, 1996
  - -------------------------------
   John L. Sprague
  
  
   /s/Philippe van Marcke             Director                     June 17, 1996
  - -------------------------------                       
  Philippe van Marcke
  
  
  
  
  
  <PAGE>   10
  
  
                                    Exhibit Index
                                    -------------
  
  
   Exhibit No.            Description of Exhibit                      Page Number
   -----------            ----------------------                      -----------
  
  
       4.1*      Restated Articles of Organization of  the Registrant
  
       4.2*      Restated By-Laws of the Registrant
  
       4.3*      Specimen certificate representing the Common Stock 
                 of the Registrant
  
       4.4*      1988 Non-Statutory Stock Option Plan
  
       4.5*      1991 Non-Statutory Stock Option Plan
  
       4.6*      1993 Stock Option Plan and Incentive Plan
  
       4.7*      1994 Stock Option and Incentive Plan
  
       4.8*      1996 Incentive Stock Option Plan
  
       4.9*      1996 Non-Employee Director Stock Option Plan
                
       4.10*     1996 Employee Stock Purchase Plan
  
       5.1       Opinion of Testa, Hurwitz & Thibeault, LLP
  
      23.1       Consent of Testa, Hurwitz & Thibeault, LLP
                 (contained in Exhibit 5.1)
  
      23.2       Consent of KPMG Peat Marwick LLP
  
      23.3       Consent of Ernst & Young LLP
  
      24.1       Power of Attorney (included as part of the signature page 
                 to this Registration Statement)
                 
  
  - ----------
  * Incorporated by reference to Exhibits to the Registrant's Registration 
    Statement on Form S-1, No. 333-1328
metadata_documents: [{"type": "S-8", "sequence": "1", "description": "SIPEX CORPORATION", "secsgml_size_bytes": 25207}]
metadata_filer: {"company-data": {"conformed-name": "SIPEX CORP", "cik": "0001007800", "assigned-sic": "3674", "irs-number": "046135748", "state-of-incorporation": "MA"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-06123", "film-number": "96582023"}, "business-address": {"street1": "22 LINNELL CIRCLE", "city": "BILLERICA", "state": "MA", "zip": "01821", "phone": "5086678700"}, "mail-address": {"street1": "22 LINNELL CIRCLE", "city": "BILLERICA", "state": "MA", "zip": "01821"}}
text: 1
      As filed with the Securities and Exchange Commission on June 17, 1996.
                                                        Registration No. 333-
  
  ==============================================================================
  
                         SECURITIES AND EXCHANGE COMMISSION
                               WASHINGTON, D.C. 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 Identification No.)
  incorporation or organization) 
  
                                  22 Linnell Circle
                           Billerica, Massachusetts 01821
                                  (508) 667-8700
                 (Address of Principal Executive Offices) (Zip Code)
  
                               ----------------------
  
                        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
                          1996 Employee Stock Purchase Plan
                              (Full title of the plans)
  
                               ----------------------
  
                                  James E. Donegan
                        President and Chief Executive Officer
                                  SIPEX Corporation
                                  22 Linnell Circle
                           Billerica, Massachusetts 01821
                                  (508) 667-8700
             (Name and address including zip code and telephone number,
                     including area code, of agent for service)
  
                               ----------------------
  
                                      Copy to:
  
                              Timothy C. Maguire, Esq.
                           TESTA, HURWITZ & THIBEAULT, LLP
                         High Street Tower, 125 High Street
                             Boston, Massachusetts 02110
                                   (617) 248-7000
  
     Approximate date of commencement of proposed sale to the public: As soon as
  practicable after this Registration Statement becomes effective.
  
                               ----------------------
  
  ==============================================================================
  2
  
                           CALCULATION OF REGISTRATION FEE
  =================================================================================
  
                                            Proposed      Proposed
                                             Maximum      Maximum
           Title of              Amount     Offering     Aggregate    Amount of
         Securities to           to be      Price Per     Offering    Registration
         be Registered         Registered     Share        Price         Fee
  - ---------------------------------------------------------------------------------
  1988 NON-STATUTORY STOCK
  OPTION PLAN
  Common Stock (Par Value $.01)        500   $11.00(1)   $     5,500    $    1.90
  
  1991 NON-STATUTORY STOCK
  OPTION PLAN
  Common Stock (Par Value $.01)    211,654   $ 0.40(1)   $    84,662    $   29.19
  
  1993 STOCK OPTION AND
  INCENTIVE PLAN
  Common Stock (Par Value $.01)     91,250   $ 0.40(1)   $    36,500    $   12.59
  
  1994 STOCK OPTION AND
  INCENTIVE PLAN
  Common Stock (Par Value $.01)    444,913   $ 0.40(1)   $   177,965    $   61.37
  
  1996 INCENTIVE STOCK
  OPTION PLAN
  Common Stock (Par Value $.01)    600,000   $18.19(2)   $10,914,000    $3,763.45
  
  1996 NON-EMPLOYEE
  DIRECTOR STOCK OPTION PLAN
  Common Stock                      50,000   $ 9.50(1)   $   475,000    $  163.79
  (Par Value $.01)                 100,000   $18.19(2)   $ 1,819,000    $  627.24
  
  1996 EMPLOYEE STOCK PURCHASE 
  PLAN
  
  Common Stock (Par Value $.01)    250,000   $18.19(2)   $ 4,547,500    $1,568.10
  
  TOTAL:                         1,748,317                              $6,227.63
  
  - ---------------------------------------------------------------------------------
  (1) All such shares are issuable upon exercise of outstanding options with fixed
      exercise prices. Pursuant to Regulation C, Rule 457(h)(1) under the
      Securities Act of 1933, as amended, the aggregate offering price and the fee
      have been computed upon the basis of the price at which the options may be
      exercised.
  
  (2) The price of $18.19 per share, which is the average of the high and low
      prices of the common stock of the registrant reported on the Nasdaq National
      Market on June 12, 1996, is set forth solely for purposes of calculating the
      filing fee pursuant to Rule 457(c) and (h) and has been used only for those
      shares without a fixed exercise price.
  3
  
                                       -3-
  
                                       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 this
  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 with the Commission are incorporated by
  reference in this Registration Statement:
  
        (a)   Registrant's Prospectus dated April 2, 1996 as filed with the
              Commission pursuant to Rule 424(b)(1) of the Securities Act of 1933,
              as amended (the "Securities Act"), on April 3, 1996; and
  
        (b)   The section entitled "Description of Registrant's Securities to be
              Registered," contained in the Registrant's Registration Statement on
              Form 8-A, filed on March 1, 1996 pursuant to Section 12(g) of the
              Securities Exchange Act of 1934, as amended (the "Exchange Act").
  
        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.
  4
                                        -4-
  
  Item 4. Description of Securities.
          --------------------------
  
        Not applicable.
  
  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.
  5
  
                                        -5-
  
  Item 7. Exemption From Registration Claimed.
          ------------------------------------
  
        Not applicable.
  
  Item 8. Exhibits.
          ---------
   
        Exhibit No.       Description of Exhibit
        ----------        ----------------------
  
        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).
  
        Exhibit 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).
  
        Exhibit 4.3       Specimen certificate representing the Common Stock
                          of the Registrant (filed as Exhibit 4.1 to the
                          Registrant's Registration Statement on Form S-1, File
                          No. 333-1328, and incorporated herein by reference).
  
        Exhibit 4.4       1988 Non-Statutory Stock Option Plan (filed as
                          Exhibit 10.1 to the Registrant's Registration Statement
                          on Form S-1, File No. 333-1328, and incorporated herein
                          by reference).
  
        Exhibit 4.5       1991 Non-Statutory Stock Option Plan (filed as
                          Exhibit 10.2 to the Registrant's Registration Statement
                          on Form S-1, File No. 333-1328, and incorporated herein
                          by reference).
  
        ExhibiT 4.6       1993 Stock Option and Incentive Plan (filed as
                          Exhibit 10.3 to the Registrant's Registration Statement
                          on Form S-1, File No. 333-1328, and incorporated herein
                          by reference).
  
        Exhibit 4.7       1994 Stock Option and Incentive Plan (filed as
                          Exhibit 10.4 to the Registrant's Registration Statement
                          on Form S-1, File No. 333-1328, and incorporated herein
                          by reference).
  
        Exhibit 4.8       1996 Incentive Stock Option Plan (filed as Exhibit
                          10.5 to the Registrant's Registration Statement on Form
                          S-1, File No. 333-1328, and incorporated herein by
                          reference).
  
        Exhibit 4.9       1996 Non-Employee Director Stock Option Plan (filed
                          as Exhibit 10.6 to the Registrant's Registration
                          Statement on Form S-1, File No. 333-1328, and
                          incorporated herein by reference).
  6
                                        -6-
  
        Exhibit 4.10      1996 Employee Stock Purchase Plan (filed as Exhibit
                          10.7 to the Registrant's Registration Statement on Form
                          S-1, File No. 333-1328, and incorporated herein by
                          reference).
  
        Exhibit 5.1       Opinion of Testa, Hurwitz & Thibeault, LLP (filed
                          herewith).
  
        Exhibit 23.1      Consent of Testa, Hurwitz & Thibeault, LLP (contained in
                          Exhibit 5.1).
  
        Exhibit 23.2      Consent of KPMG Peat Marwick LLP (filed herewith).
  
        Exhibit 23.3      Consent of Ernst & Young LLP (filed herewith).
  
        Exhibit 24.1      Power of Attorney (included as part of the signature 
                          page to 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;
  
                    (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.
  
              (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,
  7
                                        -7-
  
                    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 an 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 Securities Act of 1933 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.
  
                        [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]
  8
                                        -8-
  
                                     SIGNATURES
  
        Pursuant to the requirements of the Securities Act of 1933, the
  Registrant, SIPEX Corporation, 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 Town of Billerica, Commonwealth
  of Massachusetts, on this 17th day of June, 1996.
  
                                      SIPEX Corporation
  
                                      By:   /s/ James E. Donegan
                                            -----------------------------------
                                            James E. Donegan
                                            Chairman, Chief Executive Officer,
                                            President and Clerk
  
                                  POWER OF ATTORNEY
  
        We, the undersigned officers and directors of SIPEX Corporation hereby
  severally constitute and appoint James E. Donegan and Frank R. DiPietro, and
  each of them singly, our true and lawful attorneys, with full power to them and
  each of them singly, to sign for us in our names in the capacities indicated
  below, 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, and generally to do all things in our names and on our behalf in our
  capacities as officers and directors to enable SIPEX Corporation to comply with
  the provisions of the Securities Act of 1933, as amended, hereby ratifying and
  confirming our signatures as they may be signed by our said attorneys, or any of
  them, to said Registration Statement and all amendments thereto.
  
        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 dates indicated.
  
           SIGNATURE                     TITLE(S)                    DATE
           ---------                     --------                    ----
  
    /s/  James E. Donegan            President, Chief             June 17, 1996
   ----------------------------      Executive Officer
    James E. Donegan                 (Principal Executive
                                     Officer) and Clerk
  9
  
                                        -9-
  
             SIGNATURE                     TITLE(S)                   DATE
             ---------                     --------                   ----
  
   /s/ Frank R. DiPietro              Senior Vice President,       June 17, 1996
  - -------------------------------     Chief Financial
   Frank R. DiPietro                  Officer and
                                      Treasurer (Principal
                                      Financial Officer
                                      and Principal
                                      Accounting Officer)
  
   /s/  Daniel Deroux                 Director                     June 17, 1996
  - -------------------------------
   Daniel Deroux
  
   /s/  Manfred Loeb                  Director                     June 17, 1996
  - -------------------------------
    Manfred Loeb
  
   /s/  Lionel H. Olmer               Director                     June 17, 1996
  - -------------------------------
   Lionel H. Olmer
  
                                                      
   /s/ John L. Sprague                Director                     June 17, 1996
  - -------------------------------
   John L. Sprague
  
   /s/Philippe van Marcke             Director                     June 17, 1996
  - -------------------------------                       
  Philippe van Marcke
  10
  
                                    Exhibit Index
                                    -------------
  
   Exhibit No.            Description of Exhibit                      Page Number
   -----------            ----------------------                      -----------
  
       4.1*      Restated Articles of Organization of  the Registrant
  
       4.2*      Restated By-Laws of the Registrant
  
       4.3*      Specimen certificate representing the Common Stock 
                 of the Registrant
  
       4.4*      1988 Non-Statutory Stock Option Plan
  
       4.5*      1991 Non-Statutory Stock Option Plan
  
       4.6*      1993 Stock Option Plan and Incentive Plan
  
       4.7*      1994 Stock Option and Incentive Plan
  
       4.8*      1996 Incentive Stock Option Plan
  
       4.9*      1996 Non-Employee Director Stock Option Plan
                
       4.10*     1996 Employee Stock Purchase Plan
  
       5.1       Opinion of Testa, Hurwitz & Thibeault, LLP
  
      23.1       Consent of Testa, Hurwitz & Thibeault, LLP
                 (contained in Exhibit 5.1)
  
      23.2       Consent of KPMG Peat Marwick LLP
  
      23.3       Consent of Ernst & Young LLP
  
      24.1       Power of Attorney (included as part of the signature page 
                 to this Registration Statement)
                 
  
  - ----------
  * Incorporated by reference to Exhibits to the Registrant's Registration 
    Statement on Form S-1, No. 333-1328