Benzene ( B) and two representative chlorobenzenes (1,4-dichlorobenzene (DCB) and 1,2,3-trichlorobenzene (TCB)) were oxidized by means of UV irradiation alone, ozone alone, and the combinations UV/H2O2 and O-3/H2O2. In the single photolytic process, the influence on the photodegradation of the pH, temperature, and type of radiation source used was established. A kinetic study was performed by evaluating the first-order rate constants and the quantum yields. The effect of the additional presence of hydrogen peroxide was pointed out in the combined process UV/H2O2, with the determination of the specific contribution of the radical pathway to the overall photodegradation system. In the oxidation by ozone based systems ( ozone alone and the combination O-3/H2O2), the rate constants at 20 degrees C for the reaction of each compound with ozone and hydroxyl radicals were determined.