Cellulases are industrially important enzymes and they are produced by a variety of microorganisms. However, there are few studies on the production of these enzymes by Bacillus species there has been scarce reports on Bacillus cereus MRK1 isolated from paper sludge and its purification. Different intends such as incubation period, temperature, pH and effect of carbon and nitrogen sources were optimized for maximum yield of the enzyme. Initial optimization process showed pH 8, 32°C, xylan and yeast extract favoring enzyme production. The test strain showed its ability to secrete cellulase around 102 U/ml when it was grown in paper sludge supplemented medium. The purified cellulase recorded protein band around 60 kDa confirmed the presence of enzyme by zymogram. Purified cellulase showed its biostoning ability when applied on jean cloth. © 2012 Elsevier B.V., All rights reserved.