Recent development in titanium oxide-based photocatalysts was reviewed concerning the development in the highly dispersed titanium oxide photocatalysts prepared on or within zeolites and the visible light-responsive TiO2 photocatalysts. The unique and high reactivities of titanium oxide species anchored or incorporated in the zeolite for various photocatalytic reactions such as reduction of CO2 with H2O and direct decomposition of NO, into N-2 and O-2 were discussed focusing on the relationship between the reactivity and local structures of the catalysts. Moreover, the preparation of the visible light-responsive TiO2 photocatalysts by applying ion-engineering techniques such as an ion-implantation and an RF magnetron sputtering deposition method was discussed focusing on its unique reactivity for the decomposition of water into H-2 and O-2 with a separate evolution under sunlight irradiation. (C) 2007 Elsevier B.V. All rights reserved.