This study was conducted to produce and characterize cellulaseenzymes from Bacillus isolates and to determine the optimum conditionsfor cellulase activity. Four Bacillus isolates were used: iso 9+ fromcompost and iso13, iso23 and iso20 from soil. The four isolates (9+, 23,13 and 20) gave average cellulase activities of 2.89, 3.12, 3.48 and 3.53Unit/ml, respectively. The pH optimum for cellulases from the fourisolates was 6, and the temperature optima were 45, 60, 60 and 80°C,respectively. Cellulases from isolates 13 and 23 were more thermostableand retained 40.2% and 21.9% of their initial activities after incubationfor 110 min at 90°C. Cellulase was produced under solid statefermentation conditions in maize cobs, sorghum stover or bagassepretreated with 2% hydrochloric acid from the above four isolates as wellas from two more isolates (iso4- and iso2-) which were isolated from cowdung. Maximum cellulase activity was 3.78 Unit/ml from isolate 4- usingbagasse and maize cobs as substrate. These results demonstrated thatBacillus isolates 13, 23, 20 and 9+ produced active thermostableextracellular cellulase. Bagasse and maize cobs are suitable as substraesfor production of the enzyme cellulase under solid state fermentation.