A thermostable carboxymethyl cellulase producing Bacillus sp. CY8 was isolated from soil. The enzyme was produced and partially purified. The enzyme showed a single band with molecular weight of 49.4 kDa in SDS-PAGE analysis. The enzyme showed its optimal activity at pH 10.0 and 80°C. More than 78% of original activity of the enzyme was observed after pre-incubation at pH 7.0-12.0 at room temperature for 24 h. It conserved more than 90% of its original activity after pre-incubation at temperature ranging from 30 to 110°C for 60 min. The enzyme activity was induced at 3-30% concentrations of NaCl. In the presence of 5mM EDTA, CaCl2, ZnCl2, MgCl2 and 1,10-phenantrolin, 3mM PMSF, 0.1% tween20 and tween80, 1% SDS, tritonX-100 and β-mercaptoethanol, 0.1% HO, 8M urea, it remained 63, 76, 69, 67, 68, 70, 60, 68, 75, 67, 83, 97 and 65% of its original activity, respectively. According to TLC analysis, CMC was hydrolyzed into maltose, glucose and other oligosaccharides by CY8 CMCase. High thermostability, pH stability, detergent and antioxidant stability of Bacillus sp. CY8 CMCase make This Enzyme Useful In Textile, Detergent And Other Industries