Three synthetic copper(II) complexes exhibited remarkable catalytic activity for 4-chlorophenol (4-CP) oxidation by H2O2 in neutral and weak alkaline solution at 25 degrees C. The decomposition of H2O2 catalyzed by copper(H) complexes was investigated. The studies by fluorescence and UV-vis measurements proved that free hydroxyl radical vias not the primary reactive species for the oxidation of 4-CP. "Associative radical" LCu1-(OOH)-O-center dot was suggested as the possible predominant reactive species in this work. The reaction kinetics of 4-CP oxidation catalyzed by copper(II) complexes was studied in detail. The pH effect was explicated by the catalytic kinetics model proposed in this paper. The catalysis involved not only the activation of H2O2 by copper (II) complex to yield more reactive species LCu1-(OOH)-O-center dot, but also the formation of 4-chlorophenolate anion. A possible catalytic reaction mechanism of 4-CP oxidation was proposed. (C) 2008 Elsevier B.V. All rights reserved.