Transition-metal-free microporous and mesoporous materials were studied as heterogeneous epoxidation catalysts. MCM-41-type materials and zeolites with various porous structures and aluminium or gallium content but devoid of any transition metal were prepared and tested in the epoxidation of cyclooctene with aqueous hydrogen peroxide. The most promising catalytic results were obtained with Al-MCM-41, Ga-MCM-41, and ultra-stable zeolite Y (USY) with a low Si/Al ratio. All of these catalysts have acid sites of moderate strength. With Ga-MCM-41, 95% conversion of cyclooctene with 96% selectivity toward the epoxide was reached after 24 h of reaction. The catalyst could be recycled with no loss of catalytic properties. (C) 2007 Elsevier Inc. All rights reserved.