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Cellulose continues to account for one of earth’s most abundant biomass. Cellulase degrades cellulose, thereby making it one of the most sought after enzyme in the commercial market. This research aimed to characterize cellulase with enviable physicochemical parameters from a bacterium isolated from decaying sawdust heap. Isolated bacteria species were screened for cellulolysis. The bacterium with the largest halozone was identified by its 16S rRNA sequence. Optimum growth and cellulase production condition was determined by varying selected factors. Extracted cellulase was partially purified by Ion exchange and gel filtration chromatographic methods. The kinetic parameters were determined. Effect of selected conditions on cellulase activity was studied. Isolate A8 with 58 mm halozone had 96% sequence identity with Bacillus subtilis FJ532063. Optimum activity of 46.18 U/ml at 36 hours was recorded at pH 7, 35 ± 2°C. Yields of 18.5 and 13.5% resulted from ion exchange and gel filtration chromatography respectively. Km was found to be 0.0108 ± 0.0032 mg/ml with a Vmaxof 119.3 ± 7.4 µmol/min. Maximum activity for partially purified cellulase was recorded at pH 9.5 and 55°C with stability at 50°C; and pH 9, 35°C with stability at 45°C for crude cellulase. The study showed cellulase from Bacillus subtilis A8 as active and thermostable enough to be further exploited for industrial applications.