The possibility to produce oxidizing agents from water (mainly OH center dot radicals) in a three-compartment electrochemical cell, by heterogeneous catalytic reaction between a semiconductor and water under a superimposed electric field, was assessed for the degradation of non-biodegradable toxic organic compounds. The treated solution is not in contact with electrodes to avoid, in the case of high content of chlorine salt, chlorine and indirect chlorinated hydrocarbons generation. The specific pollutant abatement per unit power was 40 g COD1(-1) kWh(-1) when starting from a phenol concentration of 100ppmw, a comparable figure to those obtainable with the best direct anodic electro-oxidation processes. The rate of radicals generation was found to depend on several factors: imposed current density, electric field and electrical resistivity of the phases involved. (c) 2007 Published by Elsevier Ltd.