Abstract: The mechanism of the oxidation of benzene to phenol by CuO+ was investigated in details at the UB3LYP/6-31G(d,p) level of theory. Both the singlet and triplet potential energy profiles were studied. The computational results indicate that the interaction between benzene and CuO+ is mainly the ? coordination and bond, weakly back-donation ? bond also contributes. The oxidation of benzene to phenol by CuO+ proceeds through the non-radical H-abstraction mechanism, which mainly includes the C-H bond activation and the coupling of phenyl and hydroxyl. The C-H bond activation is the rate-limiting step. The entrance channel of the C-H bond activation step involves the spin cross between the singlet and triplet potential energy profiles. The oxidation of benzene to phenol by CuO+ is predicted to occur easily in the gas phase.