Exhibit 3.5

                                                                    PAGE 1
                                                    
                               State of Delaware

                       Office of the Secretary of State

                          ---------------------------


      I, EDWARD J. FREEL, SECRETARY OF STATE OF THE STATE OF DELAWARE, DO HEREBY
CERTIFY THE ATTACHED IS A TRUE AND CORRECT COPY OF THE CERTIFICATE OF AMENDMENT 
OF "CLARK USA, INC.", FILED IN THIS OFFICE ON THE FIRST DAY OF OCTOBER, A.D. 
1997, AT 11:15 O'CLOCK A.M.

     A CERTIFIED COPY OF THIS CERTIFICATE HAS BEEN FORWARDED TO THE NEW CASTLE 
COUNTY RECORDER OF DEEDS FOR RECORDING.



                                          /s/ Edward J. Freel 
                                         -----------------------------------
                                         Edward J. Freel, Secretary of State


                                    [SEAL]


                                         AUTHENTICATION:  8680762

                                                   DATE:  10-01-97


 
                            Certificate of Amendment

                                       of

                          Certificate of Incorporation

                                       of

                                Clark USA, Inc.


                 _____________________________________________

                   Adopted in accordance with the provisions
                   of Section 242 of the General Corporation
                          Law of the State of Delaware

                 _____________________________________________

     I, Maura Clark, Executive Vice President of CLARK USA, INC., a corporation
organized and existing under the laws of the State of Delaware (the
"Corporation"), hereby certify as follows:

     FIRST:  That the Restated Certificate of Incorporation of the Corporation
was filed with the Secretary of State of the State of Delaware on the 28th day
of December, 1994 and that Certificates of Amendment thereto were filed with the
Secretary of State of the State of Delaware on the 23rd day of February, 1995,
the  3rd day of November, 1995 and on two occasions on the 1st day of October,
1997 (as so amended, the "Certificate of Incorporation").

     SECOND:  That Article 4 of the Certificate of Incorporation of the
Corporation has been amended to read in its entirety as follows:

 
          ARTICLE 4.  The total number of shares of capital stock which the
     Corporation shall have the authority to issue is 68,554,552 shares,
     consisting of (a)63,554,552 shares of common stock, par value $.01 per
     share, of which (i) 54,164,597 shares shall be designated "Common Stock,"
     (ii) 3,389,955 shares shall be designated "Class D Common Stock," and (iii)
     6,000,000 shares shall be designated "Class F Common Stock", and (b)
     5,000,000 shares of "Preferred Stock," par value $.01 per share.

     A.   Preferred Stock.
          --------------- 

          1.  Issuance.  The Board of Directors is authorized, subject to
     limitations prescribed by law, to provide for the issuance of shares of
     Preferred Stock in one or more Classes, to establish the number of shares
     to be included in each such Class, and to fix the designations, powers,
     preferences and rights of the shares of each such Class, and any
     qualifications, limitations or restrictions thereof.

     B.   Common Stock.
          ------------ 

          1.  Dividends.  Subject to the preferential rights, if any, of the
     Preferred Stock, the holders of Common Stock shall be entitled to receive,
     when, as and if declared by the Board of Directors, out of the assets of
     the Corporation which are by law available therefor, dividends payable
     either in cash, in property or in shares of capital stock. The Board of
     Directors may not declare or pay any dividend or distribution with respect
     to the Common Stock unless the same dividend or distribution per share has
     been declared or paid, as the case may be, with respect to the Class D
     Common Stock and the Class F Common Stock; provided, that with respect to
     dividends payable only in shares of common stock, each of the Common Stock,
     the Class D Common Stock and the Class F Common Stock shall receive an
     equivalent dividend per share payable in common stock of the corresponding
     class.

          2.  Voting Rights.  At every annual or special meeting of stockholders
     of the Corporation, every share of Common Stock shall entitle the holder
     thereof to one vote, voting together with the holders of Class F Common
     Stock, in person or by proxy, for each share of Common Stock standing in
     his or her name on the books of the Corporation; provided that the holders
     of Common Stock shall have no voting rights with respect to matters
     reserved (by law or by agreement with the Corporation) solely for any other
     class of capital stock.

          3.  Liquidation, Dissolution or Winding Up. In the event of any
     voluntary or involuntary liquidation, dissolution or winding up of the
     affairs of the Corporation (a "Liquidation"), after payment or provision
     for payment of the debts and other liabilities of the Corporation and of
     the preferential amounts, if any, to which the holders of Preferred Stock
     shall be entitled, the holders of all outstanding shares of Common Stock
     shall be entitled to share ratably, on a share-for-share basis, with the
     holders of Class D Common Stock and Class F Common Stock in the remaining
     assets of the Corporation.

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     C.   Class D Common Stock
          ---------------------

          1.  Dividends.  Subject to the preferential rights, if any, of the
     Preferred Stock, the holders of Class D Common Stock shall be entitled to
     receive the same dividends or distributions per share, whether payable in
     cash, in property or in shares of capital stock, as may be declared and
     paid on the Common Stock and the Class F Common Stock, and the Board of
     Directors may not declare or pay any dividend or distribution with respect
     to the Class D Common Stock unless the same dividend or distribution per
     share has been declared or paid, as the case may be, with respect to the
     Common Stock  and the Class F Common Stock; provided, that with respect to
     dividends payable only in shares of common stock, each of the Common Stock,
     the Class D Common Stock and the Class F Common Stock shall receive an
     equivalent dividend per share payable in common stock of the corresponding
     class.

          2.  Voting Rights.  Holders of shares of Class D Common Stock shall
     not be accorded any voting rights in respect thereof and such shares shall
     not be deemed to be outstanding for purposes of determining the vote
     required on any matter properly brought before the stockholders of the
     Corporation for a vote thereon.

          3.  Conversion.  (a) The Company shall have the right, at any time and
     from time to time, to convert any or all of the shares of Class D Common
     Stock into an equal number of shares of Common Stock.  The method of
     selection of such shares shall be determined by the Board of Directors of
     the Company in its sole discretion.

               (b) Following an initial public offering of Common Stock, any
     person who is not an affiliate of Occidental Petroleum Corporation to whom
     shares of Class D Common Stock have been directly or indirectly transferred
     by Occidental Petroleum Corporation in an arm's-length transaction shall
     have the right, at any time and from time to time, to convert any or all of
     such shares of Class D Common Stock into an equal number of shares of
     Common Stock.

               (c) Following an initial public offering of Common Stock, any
     person who is not an affiliate of Gulf Resources Corporation to whom shares
     of Class D Common Stock have been directly or indirectly transferred by
     Gulf Resources Corporation in an arm's-length transaction shall have the
     right, at any time and from time to time, to convert any or all of such
     shares of Class D Common Stock into an equal number of shares of Common
     Stock.

          4.  Liquidation, Dissolution or Winding Up. In the event of any
     voluntary or involuntary liquidation, dissolution or winding up of the
     affairs of the Corporation (a "Liquidation"), after payment or provision
     for payment of the debts and other liabilities of the Corporation and of
     the preferential amounts, if any, to which the holders of Preferred Stock
     shall be entitled, the holders of all outstanding shares of Class D Common
     Stock shall be entitled to share ratably, on a share-for-share basis, with
     the


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     holders of Common Stock and Class F Common Stock in the remaining assets of
     the Corporation.

          5.  Anti-Dilution.  In the event the Company shall at any time (a)
     declare a dividend on any shares of capital stock of the Company or any
     securities issued in respect thereof, or in substitution therefor, in
     connection with any stock split, dividend or combination, or any
     recapitalization, merger, consolidation, exchange or other similar
     reorganization (a "Recapitalization"), such dividend being payable in
     shares of capital stock of the Company, (b) subdivide the outstanding
     capital stock of the Company, (c) combine the outstanding capital stock of
     the Company into a smaller number of shares, or (d) issue any shares of
     capital stock in a Recapitalization, the number of shares of Class D Common
     Stock then outstanding shall be proportionately adjusted so that the
     relative equity percentage ownership of the Company and the relative voting
     power represented by each such share shall be preserved as nearly as
     practicable.

     D.   Class F Common Stock
          --------------------

          1.  Dividends.  Subject to the preferential rights, if any, of the
     Preferred Stock, the holders of Class F Common Stock shall be entitled to
     receive the same dividends or distributions per share, whether payable in
     cash, in property or in shares of capital stock, as may be declared and
     paid on the Common Stock and the Class D Common Stock, and the Board of
     Directors may not declare or pay any dividend or distribution with respect
     to the Class F Common Stock unless the same dividend or distribution per
     share has been declared or paid, as the case may be, with respect to the
     Common Stock and the Class D Common Stock; provided, that with respect to
     dividends payable only in shares of common stock, each of the Common Stock,
     the Class D Common Stock and the Class F Common Stock shall receive an
     equivalent dividend per share payable in common stock of the corresponding
     class.

          2.  Voting Rights.  At every annual or special meeting of stockholders
     of the Corporation, every share of Class F Common Stock shall entitle the
     holder thereof to one vote (subject to adjustment as provided below),
     voting together with the holders of Common Stock, on all matters submitted
     to a vote of the holders of Common Stock or Class F Common Stock, in person
     or by proxy, in the same manner and with the same effect as the holders of
     Common Stock; provided that the holders of Class F Common Stock shall have
     no voting rights with respect to matters reserved (by law or by agreement
     with the Corporation) solely for any other class of capital stock; and
     provided further, that if the holders of the Class F Common Stock would
     otherwise be entitled to cast votes representing, in the aggregate, more
     than 19.9% of the total voting power of all classes of capital stock of the
     Corporation entitled to vote, then the vote allotted to each share of Class
     F Common Stock shall be proportionately reduced so that all outstanding
     shares of Class F Common Stock shall be entitled to cast votes
     representing, in the aggregate, 19.9% of the total voting power of all
     classes of capital stock of the Corporation entitled to vote.

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          3.   Conversion. Any shares of Class F Common Stock that are owned
     beneficially or of record by Occidental Petroleum Corporation and its
     affiliates shall have no conversion rights. Any holder of any shares of
     Class F Common Stock other than Occidental Petroleum Corporation and its
     affiliates shall have the right, at any time and from time to time, to
     convert any or all of such other holder's shares of Class F Common Stock
     into an equal number of shares of Common Stock.

          4.   Antidilution. In the event the Corporation shall at any time (a)
     declare a dividend on any shares of capital stock of the Corporation or any
     securities issued in respect thereof, or in substitution therefor, such
     dividend being payable in shares of capital stock of the Corporation, (b)
     subdivide the outstanding capital stock of the Corporation, or (c) combine
     the outstanding capital stock of the Corporation into a smaller number of
     shares, the provisions relating to the conversion of shares of Class F
     Common Stock into Common Stock shall be equitably and proportionately
     adjusted.

          5.   Liquidation, Dissolution or Winding Up. In the event of any
     Liquidation, after payment or provision for payment of the debts and other
     liabilities of the Corporation and of the preferential amounts, if any, to
     which the holders of Preferred Stock shall be entitled, the holders of all
     outstanding shares of Class F Common Stock shall be entitled to share
     ratably, on a share-for-share basis, with the holders of Common Stock and
     Class D Common Stock in the remaining assets of the Corporation.

     D.   Reclassification. All shares of Class E Common Stock issued and
     outstanding immediately prior to the filing of this Certificate of
     Amendment with the Secretary of State of the State of Delaware are hereby
     reclassified and, without any further action on the part of the Corporation
     or the holder of such shares, shall hereafter be deemed to have become an
     aggregate of 63,000 shares of Preferred Stock to be known as "Exchangeable
     Preferred Stock," the terms of which shall be set forth in the Certificate
     of Designations with respect to the Exchangeable Preferred Stock in the
     form of Exhibit A hereto.

     E.   Amendment of this Article. The Corporation may not amend, alter,
     change or repeal in any manner adverse to the holders of the Class D Common
     Stock or Class F Common Stock the rights or preferences of the holders of
     the Class D Common Stock or Class F Common Stock contained in this Article
     4 without the consent of the holders of 95% of the Class D Common Stock or
     the Class F Common Stock, as the case may be.

     THIRD: That such amendment has been duly adopted in accordance with the
provisions of the General Corporation Law of the State of Delaware by the
written consent of the holders of

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a majority of  all outstanding shares of each class entitled to vote thereon in
accordance with the provisions of Section 228 of the General Corporation Law.

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     IN WITNESS WHEREOF, the undersigned has signed this Certificate this 1st
day of October, 1997.

                                    CLARK USA, INC.
                                       /s/  Maura J. Clark
                                    By:_________________________________
                                    Name:   Maura J. Clark
                                    Title:  Executive Vice President &
                                            Chief Financial Officer



Attested By:

/s/ Katherine D. Knocke
__________________________
Name:  Katherine D. Knocke
Title: Secretary

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