In an attempt to improve our understanding of the basic mechanisms of the degradation of aromatic pollutants, the photocatalysed reactions of a few selected organic compounds, namely 4-bromoaniline, 3-nitroaniline, pentachlorophenol, 1,2,3-trichlorobenzene and diphenylamine has been investigated either in water or in acetonitrile/water mixture in the presence of titanium dioxide and molecular oxygen. An attempt has been made to identify the products formed during the photo-oxidation process through GC-MS analysis technique. A probable mechanism for the formation of the products has been proposed. (c) 2006 Elsevier B.V. All rights reserved.