Cellulase productions in solid state fermentation (SSF) by Trichoderma viride SL-I were conducted in a column. Periodically oscillating the temperature in the range of 30-50 degrees C in symmetrical or asymmetrical modes had no adverse effect on productivity. Effective activation of spore germination was found when the spores were treated twice at 30 degrees C for 30 min. The results are useful in the performances of SSF processes.