Exhibit 4.2




                     CERTIFICATE OF MERGER
                                
                               OF
                                
                     DIAMOND SHAMROCK, INC.
                                
                              INTO
                                
                      ULTRAMAR CORPORATION
                                
                    UNDER SECTION 251 OF THE
                                
                    GENERAL CORPORATION LAW
                                
                    OF THE STATE OF DELAWARE
                                 
     
               Pursuant to Section 251 of the General Corporation
     Law of the State of Delaware (the "GCL"), ULTRAMAR
     CORPORATION, a Delaware corporation ("ULTRAMAR"), hereby
     certifies the following information relating to the merger
     of DIAMOND SHAMROCK, INC., a Delaware corporation
     ("DIAMOND"), with and into ULTRAMAR (the "Merger"):
     
               FIRST:  The names and states of incorporation of
     ULTRAMAR and DIAMOND, which are the constituent corporations
     in the Merger (the "Constituent Corporations"), are:
     
               Name                                    State
     
               ULTRAMAR CORPORATION                    Delaware
     
               DIAMOND SHAMROCK, INC.                  Delaware
     
     
               SECOND:  The Agreement and Plan of Merger (the
     "Merger Agreement"), dated as of September 22, 1996 between
     ULTRAMAR and DIAMOND, setting forth the terms and conditions
     of the Merger, has been approved, adopted, certified,
     executed and acknowledged by each of the Constituent
     Corporations in accordance with Section 251 of the GCL.
     
               THIRD:  The name of the corporation surviving the
     Merger is Ultramar Corporation which name shall be changed
     in the Merger to Ultramar Diamond Shamrock Corporation.
     
               FOURTH:  The certificate of incorporation of
     ULTRAMAR shall be amended as follows (and as so amended
     shall be the certificate of incorporation of the corporation
     surviving the Merger until thereafter changed or amended as
     provided therein or by applicable law):
     
               a. by deleting article FIRST in its entirety and
     by inserting the following in its place:
     
               "FIRST: The name of the corporation is Ultramar
               Diamond Shamrock Corporation (hereinafter the
               "Corporation")."
     
               b. by deleting Section 1 of Article FOURTH in its
     entirety and by inserting the following in its place:
     
               "(1) The total number of shares which the
     Corporation shall have authority to issue is
     275,000,000 shares, consisting of (a) 250,000,000 shares of
     common stock, par value $.01 per share (the "Common Stock"),
     and (b) 25,000,000 shares of preferred stock, par value $.01
     per share (the "Preferred Stock")."
     
               c. by adding a new Article ELEVENTH, immediately
     following Article TENTH, which reads in its entirety as
     follows:
     
               "ELEVENTH:  With respect to any action required or
               permitted to be taken by the stockholders of the
               Corporation at any annual or special meeting, unless
               required by law or determined by the chairman of the
               meeting to be advisable, the vote on any matter,
               including the election of directors, need not be by
               written ballot."
     
               FIFTH:  An executed Merger Agreement is on file at
     9830 Colonnade Boulevard, San Antonio, Texas 78230 which is
     the address of an office of the corporation surviving the
     Merger.
     
               SIXTH:  A copy of the Merger Agreement will be
     furnished by the corporation surviving the Merger, on
     request and without cost, to any stockholder of either of
     the Constituent Corporations.

     IN WITNESS WHEREOF, this Certificate of Merger has been executed on
this 3rd day of December, 1996.
     
                               ULTRAMAR CORPORATION
                                   
                                   
                               By: /s/ PATRICK GUARINO
                                   
                               Name:  Patrick Guarino
                               Title: Senior Vice President,
                                      General Counsel and
                                      Secretary
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