This research investigates the kinetics of the aqueous-phase oxidation of toluene by ozone and ozone-hydrogen peroxide mixtures at 25 degrees C. The oxidation kinetics is first order with respect to the ozone concentration, and the reaction order in toluene varies with pH and the presence or absence of hydrogen peroxide. The peroxone oxidation is one-half order with respect to hydrogen peroxide in distilled water (initial pH of 5.4) and other solutions of higher pH. In acidic solutions with an initial pH of 3 or less, the overall kinetics is second order; the direct oxidation of toluene by ozone molecules is predominant in determining the slow rate of reaction. The reaction becomes very fast and enhanced by hydrogen peroxide, if present, in alkaline solutions with an initial pH of 10 or above. Under these conditions, the reaction is controlled by hydroxyl radical reactions and is independent of the toluene concentration in the traditional and advanced ozonation processes.