Mangroves occupy a relatively unexplored site in endophytic microorganism isolation so they can represent a new source in obtaining more enzymes with different potentialities. The present study was carried out to evaluate the ability of Bacillus sp isolated from mangrove species Rhizophora mucronata for the production of Cellulase enzyme. After production, Proteins from the culture filtrate were precipitated by Ammonium Sulfate (60%). The precipitate was reconstituted with assay buffer and dialyzed against same buffer. Then the dialyzed sample applied on DEAE Cellulose column and eluted with 1M NaCl in buffer. Purified enzyme was found to be 65KDa by SDS PAGE. The optimum conditions for the enzyme activity were found to be at a temperature 37°C and PH 7.0. The Km and Vmax values of the enzyme were 1.25mg/ml and 14.6 IU/ml, respectively.