Four processes have been used to enhance the ozonation of phenol in water: I-pH increasing (O3-pH), II- hydrogen peroxide addition (O3- H2O2), III- UV irradiation (O3- UV), and in the presence of both H2O2 and UV; IV-(O3- UV- H2O2). In each of these processes the rate of phenol degradation has two components: direct and indirect.