A H-2 generation system based on the cyanobacterial photosystem I (PSI) reconstituted with 1,4-naphthoquinone-stabilized Pt nanoparticles (PtNPs) was constructed. Irradiating the system with red light (680 nm) and using sodium L(+)-ascorbate as the sacrificial electron donor generated H-2, which was detected by GC. The light-induced H-2 generation was observed at a maximum rate of 0.026 mol H-2 h(-1) (mol PSI)(-1) using 2,6-dichloroindophenol (DCIP) as the mediator. The H-2 evolution was increased to 0.053 mol H-2 h(-1) (mol PSI)(-1) in the presence of cytochrome c (cyt c) as the mediator.