Endoglucanase (carboxymethylcellulase) production byBacillus thermoalkalophilus was both inducible and repressible. The enzyme production by free and immobilized cells was studied. Of the four entrapment matrices that were tried, polyacrylamide was the best at retaining cells at 60°C. The rate of CMCase production by immobilized cells was low initially, but increased and siabilized by day 7. Change in the metabolic behaviour of the immobilized cells was envisaged due to low oxygen consumption.