Various kinds of modified lead dioxide (PbO2) electrodes, doped with bismuth oxides and cobalt oxides, were prepared by electrodeposition in acid solution, and were characterized in terms of their morphological (SEM) and structural (XRD) features. Mineralization experiments on o-nitrophenol (ONP) in an electrocatalytic oxidation system showed that the electrocatalytic activity of Ti/Bi-PbO2 was superior to the traditional dimensionally stable anodes (DSAs) Ti/ss-PbO2 and other modified PbO2 electrodes. The mineralization, reaction kinetics and nitro-group transformation of nitrophenols (ONP, p-nitrophenol (PNP) and m-nitrophenol (MNP)) on Ti/Bi-PbO2 electrodes were studied and compared. NPs were degraded completely under the present experimental conditions by applying a 30 mA cm(-2) current density at pH 4.3 in 0.1 M Na2SO4 and 0.01 M NaCl. The degradation of NPs lay in the order: ONP > MNP > PNP. A simple degradation mechanism model is proposed.