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                                                                    EXHIBIT 31.1

                                 CERTIFICATIONS

    CERTIFICATION PURSUANT TO RULE 13A-14(A) AND 15D-14(A) OF THE SECURITIES
                              EXCHANGE ACT OF 1934

I, Luis Marin, President and Chief Executive Officer of CITGO Petroleum
Corporation (the "registrant"), certify that:

1. I have reviewed this quarterly report on Form 10-Q for the quarter ended
   September 30, 2003 of the registrant;

2. Based on my knowledge, this report does not contain any untrue statement of a
   material fact or omit to state a material fact necessary to make the
   statements made, in light of the circumstances under which such statements
   were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial
   information included in this report, fairly present in all material respects
   the financial condition, results of operations and cash flows of the
   registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officer and I are responsible for
   establishing and maintaining disclosure controls and procedures (as defined
   in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant and have:

   a) Designed such disclosure controls and procedures or caused such disclosure
   controls and procedures to be designed under our supervision, to ensure that
   material information relating to the registrant, including its consolidated
   subsidiaries, is made known to us by others within those entities,
   particularly during the period in which this report is being prepared;

   b) Evaluated the effectiveness of the registrant's disclosure controls and
   procedures and presented in this report our conclusions about the
   effectiveness of the disclosure controls and procedures, as of the end of the
   period covered by this report based on such evaluation, and;

   c) Disclosed in this report any change in the registrant's internal control
   over financial reporting that occurred during the registrant's most recent
   fiscal quarter that has materially affected, or is reasonably likely to
   materially affect, the registrant's internal control over financial
   reporting; and

5. The registrant's other certifying officer and I have disclosed, based on our
   most recent evaluation of internal control over financial reporting, to the
   registrant's auditors and the audit committee of the registrant's board of
   directors (or persons performing the equivalent function):

   a) All significant deficiencies and material weaknesses in the design or
   operation of internal control which are reasonably likely to adversely affect
   the registrant's ability to record, process, summarize and report financial
   information; and

   b) Any fraud, whether or not material, that involves management or other
   employees who have a significant role in the registrant's internal control
   over financial reporting.

Date: November 10, 2003                        /s/     Luis Marin
                                               ---------------------------------
                                               Name:   Luis Marin
                                               Title:  Chief Executive Officer