A kinetics study on the phenol oxidation by catalytic wet air oxidation (CWAO) using aqueous copper nitrate as homogeneous catalyst is presented. Based on the free radical mechanism a kinetics model is established where the electron transfer from copper to phenol is assumed to initiate the formation of free radicals. According to this model, the reaction orders are found to be approximately 1.0, 0.5 and 0.5 with respect to phenol, oxygen and copper concentrations, respectively. In order to verify the proposed kinetics, a series of CWAO experimental tests were done at various temperatures (313-333 K), oxygen partial pressures (0.6-1.9 MPa), and copper concentrations (0-13 mg1(-1)). The experimental data were found to agree well with the model. (C) 2003 Elsevier Science Ltd. All rights reserved.