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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(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)) 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(s) 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 24, 2008

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