A photosynthetic bacterium having ability to produce H-2 from acetic, butyric and lactic acids, Rhodobacter sp. M-19 was isolated. H-2 was produced from starch in a batch culture by Clostridium butyricum and in a two-step batch culture by C. butyricum and Rhodobacter sp. M-19 in yields of 1.9 and 3.6 mol H-2/mol glucose, respectively. A mixed culture of C. butyricum and Rhodobacter sp. M-19 produced H-2 from starch with a yield of 6.6 mol H-2/mol glucose in a fed-batch culture.