Cellulosic plant and waste materials are potential resources for fermentative hydrogen production. In this study, hydrogen producing, cellulolytic cultures were enriched from compost material at 52, 60 and 70 degrees C. Highest cellulose degradation and highest H(2) yield were 57% and 1.4 mol-H(2) mol-hexose(-1) (2.4 mol-H(2) mol-hexose-degraded(-1)), respectively, obtained at 52 degrees C with the heat-treated (80 degrees C for 20 min) enrichment culture. Heat-treatments as well as the sequential enrichments decreased the diversity of microbial communities. The enrichments contained mainly bacteria from families Thermoanaerobacteriaceae and Clostridiaceae, from which a bacterium closely related to Thermoanaerobium thermosaccharolyticum was mainly responsible for hydrogen production and bacteria closely related to Clostridium cellulosi and Clostridium stercorarium were responsible for cellulose degradation. (C) 2010 Elsevier Ltd. All rights reserved.