The effect of wet oxidation on the surface properties of activated carbons (ACs) with the HNO3(N), H2O2(H) and H2SO4(S) aqueous solutions, and the role of surface properties of ACs in the adsorption and reduction of NO over CuO catalyst were studied. The results show that the treatment of wet oxidation can increase the amount of surface oxygen groups on carbon, resulting in the improvements of CuO dispersion and NO adsorption on carbon. Among them, CuO/AC-N (CuO supported on AC pretreated with HNO3 aqueous solution) shows largest amount of the active surface oxygen groups, and CuO/AC-H behaves the highest capacity of NO adsorption. For the catalytic reduction of NO over CuO/ACs, the amount of active oxygen-containing groups and NO adsorption capacity on the active sites determine the performance of catalyst, in which the adsorption of NO may be the rate-limiting step, especially for the catalysts supported on ACs wet-oxidized. Over CuO/AC-H, the conversion of NO can reach 100% at 272 degrees C. (C) 2008 Elsevier B.V. All rights reserved.