The activated carbon-MnO2 catalyst has been prepared by the dipping-calcination method with activated carbon used as a carrier. The catalyst is used for catalyzing/degrading simulated o-chlorophenol wastewater with chlorine dioxide as oxidant. The COD removal efficiency by catalytic oxidation is 93.5% at the condition of wastewater's COD is 2085 mg/l, the pH value is 1.2, the dosage of chlorine dioxide is 1000 mg/l, the dosage of activated carbon-MnO2 catalyst is 6 g by reacting 60 min. The COD removal efficiency by catalytic oxidation is great than that of chemical oxidation. The catalytic activity of the catalyst only decreased a small amount in terms of COD removal efficiency after using 11 times. The COD removal efficiency is 80-90% during the continuity wastewater treatment experiment, which indicates that the wastewater treatment process is practical. The FTIR spectra indicate that the active ingredient of manganese dioxide is linked with activated carbon by chemical bond, not merely mechanical blending. (C) 2010 Elsevier B.V. All rights reserved.