Abstract:Microorganisms play a key role in bio-hydrogen producing. Progress in microorganisms producing hydrogen by anaerobic metabolism is reviewed in recent years in the present paper. The species of microorganisms producing hydrogen by anaerobic metabolism, and current status of breeding and application of efficient hydrogen-producing microorganisms were summarized. The hydrogen-production capability, substrates utilization, and metabolic characteristics of anaerobic and thermophilic hydrogen-producing microorganisms were summarized especially, the species and metabolic characteristics of thermophilic carboxydotrophic hydrogenogenic bacterium were introduced briefly.