Cellulase and beta-glucosidase production on steam pretreated spruce (SPS) with Trichoderma reesei Rut C30, Trichoderma atroviride TUB F-1505 and TUB F-1663 was investigated. The enzymes were compared in term of activity, temperature optima and hydrolytic capacity. The T. atroviride cellulases proved to have lower temperature optima for filter paper activity (FPA) assay (50 degrees C) and for hydrolysis of SPS (40 degrees C) than the Rut C30 enzymes (60 degrees C for FPA and 50 degrees C for hydrolysis). Due to high levels of extracellular beta-glucosidases, the T. atroviride enzyme supernatants hydrolyzed the washed SPS to glucose more efficiently than the enzymes produced by T. reesei. On the other hand, when the whole fermentation broths were used instead of the supernatants, thus the mycelium bound enzymes were also present, the hydrolytic capacity of T. reesei Rut C30 was enhanced by approximately 200%, while an improvement of only 15% was observed in case of the T atroviride isolates. (C) 2008 Elsevier Ltd. All rights reserved.