||An overall water splitting into hydrogen and oxygen is one of the attractive candidates for a clean and recyclable hydrogen production. Photocatalytic decomposition of water under solar light irradiation could be an ideal solution for the reaction. It has been already established that under UV light irradiation catalytic decomposition of water proceeds steadily with considerably high quantum efficiencies on several heterogeneous photocatalysts. Recently, we have started a CREST (Core Research for Evolutional Science and Technology) project to develope the more advanced photocatalysts for water decomposition supported by Japan Science and Technology Co. (JST). In this paper some of the catalysts developed in the project are described.