Oxidation of cyclohexene by cheap and environmentally friendly oxidants, namely H2O2 and CO2 has been catalyzed by Co1.5PW12O40. It has been found that the main products of the oxidation are 2-cyclohexen-l-one (enone), 2-cyclohexen-l-ol (enol) and 1, 2-cyclohexanediol (diol) with the enone as the major product. Oxidation by CO2 along with H2O2 remarkably increased the conversion compared to that by CO2 and H2O2 separately. This might be due to the fact that CO2 increases the percarbonate species (HCO4 (-)) responsible of the oxidation by oxygen transfer, which indicated that the CO2/H2O2 mixture is a useful reagent system. The decrease of both the selectivity of the enone and epoxide in favor of that of diol at higher conversions indicated that the diol was formed from the epoxide by consecutive reaction and/or directly from cyclohexene.