In this paper, experiments were conducted to investigate H-2 production from glucose by mixed anaerobic cultures at various temperatures in the mesophilic range. Results showed that glucose degradation rate and efficiency, H-2 yield, and growth rate of H-2-producing bacteria all increased as the temperature increased from 33 to 41 degrees C. However, the specific H-2 production rate increased with increasing temperature from 33 to 39 degrees C, then decreased as the temperature was further increased to 41 degrees C. The distribution of aqueous products was also greatly influenced by temperature variation. H-2 yield and growth rate of H-2-producing cultures had a linear relationship with temperature. A modified Gompertz model was able to adequately describe the H-2 production and microbial growth in the mesophilic range. The activation energies for H-2 production and microbial growth were estimated as 107.66 and 204.77 kJ/mol, respectively. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.