The photodegradation of linuron, which is one of phenylurea herbicides, was carried out in the presence of Fenton reagent. The degradation rate was strongly influenced by the pH and initial concentrations of H2O2 and Fe(II). An initial linuron concentration of 10mgL(-1) was completely degraded after 20 min under the optimum conditions. The decrease of TOC as a result of mineralization of linuron was observed during the photo-Fenton process. The degree of linuron mineralization was about 90% under UV irradiation after 25 It. The formations of chloride, nitrate and ammonium ions as end-products were observed during the photocatalytic system. The decomposition of linuron gave eight kinds of intermediate products. The degradation mechanism of linuron was proposed on the base of the evidence of the identified intermediates. Based on these results, the photo-Fenton reaction could be a useful technology for the treatment of wastewater containing linuron. (c) 2005 Elsevier B.V. All rights reserved.