A synthesized gamma-MnO2 octahedral molecular sieve was characterized and used to catalyze solvent-free atmospheric oxidation of toluene with molecular oxygen. The gamma-MnO2 showed excellent catalytic activity and good selectivity under the mild atmospheric reflux system at a low temperature (110 degrees C). Under optimized conditions, a 47.8% conversion of toluene, along with 57% selectivity of benzoic acid and 15% of benzaldehyde were obtained. The effects of reaction time, amount of catalyst and initiator, and the reusability of the catalyst were investigated. (C) 2008 Elsevier B.V. All rights reserved.