Cellulase production was carried out by solid state fermentation using corncob residue, a lignocellulosic waste from the xylose industry, as the substrate of Trichoderma reesei ZU-02. The effects of water content, dosage of wheat bran and initial pH value in solid substrate on cellulase synthesis were studied in shallow tray fermenters. The solid substrate could be reused in at least three batches and the highest cellulase activity (158 IFPU/g koji) was obtained in the second fermentation batch. To produce cellulase on a larger scale, a deep trough fermenter with forced aeration was used and 128 IFPU/g koji (similar to 305 IFPU/g cellulose) was reached after 5 days solid state fermentation. The enzyme koji produced in the present process can be used directly to hydrolyze corncob residue effectively, when the cellulase dosage was above 20 IFPU/g substrate, the saccharification yield could be over 84%. (C) 1999 Elsevier Science Ltd. All rights reserved.