The photocatalytic oxidative degradation of 2-methylthiophene has been investigated in aqueous suspensions of TiO2. The nature of the degradation products was investigated using GC/MS. The effects of the nature of the solvent and type of radiation have also been examined. In the degradation of 2-methylthiophene several intermediates were detected including hydroxythiophenes, various dimeric and trimeric structures. (C) 2001 Published by Elsevier Science B.V.