A photoinduced-H-2 production system, coupling cellulose degradation by cellulase and glucose dehydrogenase (GDH) and H-2 production with colloidal Pt as a catalyst using the visible light-induced photosensitization of Mg chlorophyll a, has been developed. When the sample solution containing methylcellulose, cellulase, GDH, NAD(+), Mg chlorophyll a, Methyl viologen and colloidal Pt was irradiated, continuous H-2 production was observed. The amount of H-2 production was about 12 mumol after 4 h irradiation.