The degradation of 2-chlorophenol in water was kinetically investigated using the following different techniques, employed either separately or simultaneously, always with the same experimental set-up: light irradiation (315-400 nm), sonication, photocatalysis with different types of TiO2, photocatalysis with sonication. The influence of the reaction volume and of different gas mixtures, containing Ar and O-2, as well as O-2/O-3, was also investigated. Finally, an energetic comparison among these different techniques was performed, focused on an industrial application of some of them. (C) 2001 Elsevier Science B.V. All rights reserved.