The photocatalytic reaction in the partial oxidation of alpha-methylstyrene (alpha-MS) to acetophenone (AP) was investigated for TiO2 supported on H-ZSM-5 (H-MFI), H-mordenite (H-MOR), and H-Y-type (H-FAU) zeolites. XRD results demonstrated that the anatase was the stable phase of TiO2 supported on zeolites. Photocatalytic activities of supported catalysts decreased in the following order: TiO2/H-MFI "TiO2/H-MOR > (TiO2) > TiO2/H-FAU" (blank). TiO2/H-MFI catalyst exhibited the best performance for photocatalytic oxidation of alpha-MS to AP. The maximal activity was obtained by 25 wt% TiO2/H-ZSM-5. The addition of water to the reaction solvent resulted in significantly lowering the photocatalytic activity for TiO2/H-ZSM-5 catalyst, although its activity for TiO2 and TiO2 + H-ZSM-5 mechanical mixture was little influenced by the amount of water added to reaction solvent. (C) 2009 Elsevier Ltd. All rights reserved.