Xenobiotic compounds are used in considerable quantities in leather industries besides organic and inorganic compounds. These compounds resist biological degradation and thus they remain present in the treated wastewater in the unaltered molecular configurations. Immobilization of organisms in carrier matrices protects them from shock load applications and from the toxicity of chemicals in bulk liquid phase. Rice Bran based Activated Carbon (RBAC) has been considered in the present study as the carrier matrix for the immobilization of Bacillus sp. isolated from Effluent Treatment Plant (ETP) employed for the treatment of wastewater containing sulphonated phenolic (SP) compounds. The influence of temperature, pH, concentration, particle size, mass of the adsorbent were observed on the immobilization behaviour of Bacillus sp. in RBAC. The percentage immobilization of Bacillus sp. was maximum at pH 7.0, temperature 20degreesC and for particle size 300 mu. Enthalpy, free energy and entropy of adsorption were -46.9 kj mole(-1), -1.187 kj mole(-1) and -161.36 J degreesK(-1) mole(-1) respectively at pH 7.0, temperature 30degreesC and particle size 600 mu. Higher values of DeltaHdegrees indicate the firm bonding of the Bacillus sp. in RBAC.