Efficient conversion of beer lees wastes into biohydrogen gas by microorganisms was reported for the first time. Batch tests were carried out to analyze influences of several environmental factors on yield of H-2 from beer lees wastes. The maximum yield of H2 68.6ml HA TVS was observed, the value is about 10-fold as compared with that of raw beer lees wastes. The hydrogen content in the biogas was more than 45% and there was no significant methane observed in this study. In addition, biodegradation characteristics of the substrate were also discussed. The results indicated that the HCl pretreatment of the substrate plays a key role in the conversion of the beer lees wastes into biohydrogen by the cow dung composts. (c) 2005 Elsevier Ltd. All rights reserved.