Some noble metals have been studied as H-2 evolution promoters for TaON, a visible light driven oxynitride photocatalyst. H-2 evolution on TaON photocatalyst under visible light irradiation (420 nm less than or equal to lambda less than or equal to 500 nm) in an aqueous methanol solution was found to be remarkably enhanced by adding Ru as a noble metal co-catalyst. (C) 2004 Elsevier B.V. All rights reserved.