The review presents the chlorophenols photo-degradation kinetics and mechanism in the aquatic environment under UV-vis in the presence of hydroxyl radicals and singlet oxygen. The influence of experimental parameters e.g. PH, dissociation degree, presence of oxidants in solution, number and position of Cl atoms on the quantum yield and reaction rate constant of chlorophenols are discussed. Mechanisms of photolysis, reaction with hydroxyl radicals, singlet oxygen and secondary reactions for mono-, di-, tri-, tetra- and pentachlorophenol are proposed. The pathways for intermediate reactions e.g. dechlorination, oxidation, dimerization for chlorophenols are also presented. (c) 2005 Elsevier B.V. All rights reserved.