EXHIBIT 23

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in Registration Statement Nos. 333-153758, 333-150720, 333-131945, 333-108790, 333-104732, 333-62566, and 333-53449 on the respective Forms S-8 of our report dated December 12, 2008, relating to the consolidated financial statements of American Pacific Corporation (which report expresses an unqualified opinion and includes explanatory paragraphs relating to the adoption of Statement of Financial Accounting Standards No. 158, Employers’ Accounting for Defined Benefit Pension and other Postretirement Plans — an Amendment of FASB Statements No. 87, 88, 106, and 132(R), and Financial Accounting Standards Board Interpretation No. 48, Accounting for Uncertainty in Income Taxes) and the effectiveness of American Pacific Corporation’s internal control over financial reporting, appearing in this Annual Report on Form 10-K of American Pacific Corporation for the year ended September 30, 2008.

/s/ Deloitte & Touche LLP

Las Vegas, Nevada
December 12, 2008