Advanced oxidation processes (AOPs) using UV, UV/H2O2, Fenton and photo-Fenton treatment were investigated at laboratory scale for aqueous solutions of 2,4-dichlorophenol (DCP). The effects on degradation of different reactant concentrations, irradiation time, temperature and pH were assessed. DCP removal, TOC mineralization, dechlorination and change in oxidation state were monitored. UV photolysis was less efficient for total DCP degradation than other AM. In contrast, photo-Fenton reaction in acidic conditions led to a higher DCP degradation in a short time. Sixty minutes of treatment were sufficient for 100% DCP removal with 75 mg l(-1) H2O2 and 10 mg l(-1) Fe(H) initial concentrations. In these conditions, a first-order degradation constant for DCP of 0.057 min 1 was obtained. (C) 2003 Elsevier B.V. All rights reserved.