Co2+ exchanged supported 12-tungstophosphoric acid was synthesized and characterized. Its catalytic activity was evaluated for the oxidation of alkenes such as styrene, cyclohexene and cis-cyclooctene under mild conditions. The superiority of the catalyst lies efficiently in catalyzing the non-solvent liquid phase oxidation of alkenes, especially oxidation of cyclohexene with 98% conversion and 57% selectivity for cyclohexene oxide, with molecular oxygen at 1 atm pressure. The active intermediate, responsible for the oxidation of alkenes, was also isolated and characterized by ESR. Its catalytic activity was evaluated for the oxidation of styrene under optimized conditions. Based on the above study a probable reaction mechanism was also proposed. (C) 2010 Elsevier B.V. All rights reserved.