A strain of Bacillus brevis has been isolated and identified based on biochemical results. Phenol biodegradation in a batch reactor was studied using the pure culture of B. brevis. The isolated strain was optimized for various environmental conditions and the biodegradation of phenol was maximum at pH 8.0, 5% (v/v) of inoculum size and without any co-substrate. The kinetics of biodegradation according to Haldane's equation mu = mu(max)S/(K-s + S+ (S-2/K-i)) adequately describes cell growth with kinetic constants in the ranges mu(max) = 0.026-0.078 h(-1), K-s = 2.2-29.31 mg/l, K-i = 868.0-2434.7 mg/l. These values are specific for this organism and we have compared with literature for pure or mixed cultures degrading phenol. (c) 2005 Elsevier B.V. All rights reserved.