Exhibit 32.1

              CERTIFICATION PURSUANT TO SECTION 1350 OF CHAPTER 63
                         OF TITLE 18 UNITED STATES CODE

         Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (subsections
(a) and (b) of Section 1350, Chapter 63 of Title 18, United States Code), the
undersigned officer of CITGO Petroleum Corporation (the "Registrant"), does
hereby certify, to his knowledge, that:

         The Annual Report on Form 10-K for the fiscal year ended December 31,
2003 of the Registrant fully complies with the requirements of Section 13(a) or
15(d) of the Securities Exchange Act of 1934 and information contained in the
Form 10-K fairly presents, in all material respects, the financial condition and
results of operations of the Registrant.

Dated: March 27, 2004                            /s/    Luis E. Marin
                                                 -------------------------------
                                                 Name:  Luis E. Marin
                                                 Title: Chief Executive Officer