Oxidation of cycloolefins was effectively performed under aerobic (1 atm dioxygen) and mild solvent-free conditions using mesoporous CrMCM-41 molecular sieve catalyst. For instance, Cycloolefins (C-5-C-7) were selectively oxidized to the corresponding alpha,beta-unsaturated ketones (for example, cyclohexene - 52.2% conversion and 71.2% selectivity) and cycloolefins (C-8-C-12) were oxidized to epoxides (for example, cis-cyclooctene - 50% conversion and >99% selectivity) at 323-353 K for 24 h. The catalytic activity over recycled catalyst remains nearly same. (C) 2008 Elsevier B.V. All rights reserved.