**EXHIBIT31.2**

 

**CERTIFICATIONPursuant to Section 302 of the Sarbanes-Oxley Act of 2002**

 

I, John Poyhonen, certifythat:

 

1.                                       I have reviewed this annual report on Form 10-Kof Senomyx, Inc.

 

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

 

3.                                       Based on myknowledge, the financial statements, and other financial information includedin this annual report, fairly present in all material respects the financialcondition, results of operations and cash flows of the registrant as of, andfor, the periods presented in this report;

 

4.                                       The registrant’s other certifying officer andI are responsible for establishing and maintaining disclosure controls andprocedures (as defined in Exchange Act Rules 13a-15(e) and15d-15(e)) for the registrant and we have:

 

a)                                      Designed such disclosure controls andprocedures, or caused such disclosure controls and procedures to be designedunder our supervision, to ensure that material information relating to theregistrant is made known to us by others within those entities, particularlyduring the period in which this report is being prepared;

 

b)                                     Evaluatedthe effectiveness of the registrant’s disclosure controls and procedures andpresented in this quarterly report our conclusions about the effectiveness ofthe disclosure controls and procedures, as of the end of the period covered bythis report based on such evaluation; and

 

c)                                      Disclosed in this annual report any change inthe registrant’s internal control over financial reporting that occurred duringthe registrant’s most recent fiscal quarter (the registrant’s fourth fiscalquarter in the case of an annual report) that has materially affected, or isreasonably likely to materially affect, the registrant’s internal control overfinancial reporting; and

 

5.                                       The registrant’s other certifying officer andI have disclosed, based on our most recent evaluation of internal control overfinancial reporting, to the registrant’s auditors and the audit committee ofthe registrant’s board of directors (or persons performing the equivalent functions):

 

a)                                      All significant deficiencies and materialweaknesses in the design or operation of internal control over financialreporting which are reasonably likely to adversely affect the registrant’sability to record, process, summarize and report financial information; and

 

b)                                     Any fraud, whether or not material, thatinvolves management or other employees who have a significant role in theregistrant’s internal control over financial reporting.

 

 
| Date: March 8, 2005 | /S/ JOHN POYHONEN                                        |
|--------------------------|----------------------------------------------------------|
|                     | John  Poyhonen                                           |
|                     | Vice  President and Chief Financial and Business Officer |

 

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