The activity of the extracellular cellulolytic complex of Trichoderma reesei upon crystalline cellulose was studied in the range of 4-10% moisture (dry basis) and 20-90 degrees C temperature with the aid of a central composite experimental design. An empirical model was established for both the endoglucanase and synergistic endo- and exoglucanase activities with a significance level >95%. The thermal stability of the cellulolytic complex adsorbed onto cellulose at low moisture conditions was determined and compared with that of the enzyme in liquid form; the former was more stable.