**EXHIBIT 31.1**
**Rule 13a-14(c) Certification of Chief Executive Officer**
CERTIFICATIONS
I, John R. Gibson, certify that:
 1.  I have reviewed this quarterly report on Form 10-Q of American Pacific Corporation(the “registrant”);  2.  Based on my knowledge, this report does not contain any untrue statement of amaterial fact or omit to state a material fact necessary to make the statements made, inlight of the circumstances under which such statements were made, not misleading withrespect to the period covered by this report;  3.  Based on my knowledge, the financial statements, and other financial informationincluded 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 periodspresented in this report;  4.  The registrant’s other certifying officer and I are responsible for establishingand maintaining disclosure controls and procedures (as defined in Exchange Act Rules13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined inExchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:
 a)  designed such disclosure controls and procedures, or caused suchdisclosure controls and procedures to be designed under our supervision,to ensure that material information relating to the registrant, includingits consolidated subsidiaries, is made known to us by others within thoseentities, particularly during the period in which this annual report isbeing prepared;  b)  designed such internal control over financial reporting, or caused suchinternal control over financial reporting to be designed under oursupervision, to provide reasonable assurance regarding the reliability offinancial reporting and the preparation of financial statements forexternal purposes in accordance with generally accepted accountingprinciples;  c)  evaluated the effectiveness of the registrant’s disclosure controls andprocedures and presented in this report our conclusions about theeffectiveness of the disclosure controls and procedures, as of the end ofthe period covered by this annual report based on such evaluation; and  d)  disclosed in this report any change in the registrant’s internal controlover financial reporting that occurred during the registrant’s most recentfiscal quarter (the registrant’s fourth fiscal quarter in the case of anannual report) that has materially affected, or is reasonably like tomaterially affect, the registrant’s internal control over financialreporting; and
 5.  The registrant’s other certifying officer and I have disclosed, based on our mostrecent evaluation of internal control over financial reporting, to the registrant’sauditors and the audit committee of registrant’s board of directors (or personsperforming the equivalent functions):
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 a)  all significant deficiencies and material weaknesses in the design oroperation of internal control over financial reporting which arereasonably 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 otheremployees who have a significant role in the registrant’s internal controlover financial reporting.     Date: February 10, 2005 By:      /s/  JOHN R. GIBSON    
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