SUMMARYTwenty-one species of thermophilic and thermotolerant fungi were tested for the ability to degrade cellulose and lignocellulose.Thielavia thermophilais newly described as cellulolytic. OnlyChrysosporium pruinosumandSporotrichum pulverulentumwere found to degrade lignocellulose extensively. In a number of cases the moisture content of the solid substrate influenced degradation by the species tested.