Nearly all of the filter paper, endoglucanase and β-glucosidase activities of T. harzianum E58 were located extracellularly, with low amounts of these activities detected in the cell extracts and relatively little associated with the cell wall. Most of the filter paper and endoglucanase activities of T. reesei C30 were detected extracellularly. The half lives of the different cellulase activities were assayed at various temperatures over a period of time. When the pH of the filtrate was adjusted to 4.8, the cellulase activities were considerably enhanced, with the average half-life at 50°C extended to 25 hrs. When various lignocellulosic substrates were hydrolyzed by T. harzianum E58 cellulases approximately 90% of the reducing sugars were present as glucose while 50–60% of the reducing sugars were detected as glucose when T. reesei C30 cellulases were used.