Oxidation of p-methoxyphenol (pmp) in aqueous solution on bismuth-doped lead oxide was studied, and the effects of the initial pmp concentration, applied potential and hydrodynamic conditions upon the oxidation rate were identified. Under all conditions studied, the concentration decay of pmp during electrooxidation follows first-order reaction kinetics. Through analysis of rotating ring-disc currents, the faradaic efficiencies for oxidation at various concentrations of pmp in solution were determined. Using u.v.-vis. and (HRMN)-R-1 spectroscopy for solution analysis, it is shown that partial oxidation of pmp occurs in chloride-free aqueous solutions. The principal products were p-benzoquinone and maleic acid, with low production of CO2 up to 1000 C dm(-3) charge. Mineralization to CO2 was considerably improved upon addition of chloride ions to the solution. In situ FTIR spectra of the electrode surface during electrolysis indicated that the presence of chloride ions enhances the mineralization of pmp by reaction of benzoquinone with anodically generated hypochlorite.