Calcination of a cerium-S-phenylene-O-holmium-O-phenylene-S hybrid copolymer under a vacuum gave cerium oxide-carbon cluster-holmium oxide composite material. The material calcined at 600 degrees C loaded with Pt particles could decompose water to H-2 and O-2 with a H-2/O-2 ratio of 2 under visible light irradiation. ESR spectral examinations of the calcined materials revealed the possibility of a two-step electron transfer in the process of CeO2 -> carbon cluster -> Ho2O3 -> Pt with an oxidation site at CeO2 particles and a reduction site at Pt particles. (c) 2005 Published by Elsevier Inc.