Benzene removal in free and immobilized cells on polyurethane foam (PUF) and polyvinyl alcohol (PVA)alginate beads was studied using an indigenous soil bacterium Bacillus sp. M3 isolated from petroleumcontaminated soil. The important process parameters (pH, temperature and inoculums size) were optimized and found to be 7, 37 degrees C and 6.0 x 10(8) CFU/mL, respectively. Benzene removals were observed to be 70, 84 and 90% within 9 days in a free cell, immobilized PVA-alginate beads and PUF, respectively under optimum operating conditions. FT-IR and GC-MS analysis confirm the presence of phenol, 1,2benzenediol, hydroquinone and benzoate as metabolites. The important kinetic parameter ratios (mu(max)/ K-s; L/mg.day) calculated using Monod model was found to be 0.00123 for free cell, 0.00159 for immobilized alginate beads and 0.002016 for immobilized PUF. Similarly inhibition constants (K-i;mg/L) calculated using Andrew-Haldane model was found to be 435.84 for free cell, 664.25 for immobilized alginate beads and 724.93 for immobilized PUF. (C) 2017 Elsevier Ltd. All rights reserved.