Hydrogen production from waste using photosynthetic bacteria is an attractive methodology. A combination of purple nonsulfur photosynthetic bacteria and anaerobic bacteria is ideal for the efficient conversion of wastewater into hydrogen. In this paper, photohydrogen production using effluent from different hydrogen fermentation reactors was carried out using two strains of photosynthetic purple nonsulfur bacteria. The results indicated that the effluent from the hydrogen fermentation reactors could be used directly for photohydrogen production without aeration or dilution pretreatment. Effluent from the carbohydrate fed hydrogen fermentation reactors is more suitable for photohydrogen production than effluent from a peptone fed reactor. Among the initial dark hydrogen fermentation stage effluents from the three carbohydrate fed reactors (CSTR, ASBR, UASB), CSTR effluent was the most suitable for photohydrogen production. (C) 2002 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.