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                                                                    Exhibit 12.1

                                  CERTIFICATION

I, Sterling Du, certify that:

     1.   I have reviewed this annual report on Form 20-F of O2Micro
          International Limited;

     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 company as of, and for, the periods presented in this report;

     4.   The company'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)) and internal
          control over financial reporting (as defined in Exchange Act Rules
          13a-15(f) and 15d-15(f)) for the company 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
          company, 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) Designed such internal control over financial reporting, or caused
          such internal control over financial reporting to be designed under
          our supervision, to provide reasonable assurance regarding the
          reliability of financial reporting and the preparation of financial
          statements for external purposes in accordance with generally accepted
          accounting principles;

          c) Evaluated the effectiveness of the company'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

          d) Disclosed in this report any change in the company's internal
          control over financial reporting that occurred during the period
          covered by the annual report that has materially affected, or is
          reasonably likely to materially affect, the company's internal control
          over financial reporting; and

     5.   The company's other certifying officer and I have disclosed, based on
          our most recent evaluation of internal control over financial
          reporting, to the company's auditors and the audit committee of the
          company'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 company'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 company's internal
          control over financial reporting.

Date: June 10, 2004


                                         By:           /s/ STERLING DU
                                             -----------------------------------
                                                         Sterling Du
                                           President and Chief Executive Officer