<PAGE>


                                                                    EXHIBIT 31.2

I, Paul G. Vanderhoven, certify that:

     1.  I have reviewed this quarterly report on Form 10-Q of Sterling
         Chemicals, Inc.;

     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(s) 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 (the registrant's fourth
              fiscal quarter in the case of an annual report) 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(s) 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
         functions):

              (a) All significant deficiencies and material weaknesses in the
              design or operation of internal control over financial reporting
              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: May 12, 2004


                  /s/ PAUL G. VANDERHOVEN
                  -----------------------------------
                  Paul G. Vanderhoven
                  Senior Vice President - Finance and Chief Financial Officer