The aim of this work was to study the biodegradation of Malathion in batch and continuous packed bed (Polyurethane foam; PUF) bioreactor (PBBR). After 10 days, 89% Malathion removal was observed in batch PBBR. Continuous PBBR was operated at various flow rates (5-30 mL/h) under optimum condition over a period of 75 days. Inlet loading rates and elimination capacities were observed in the range of 36-216 and 7.20-145.4 mg/L/day with an average removal efficiency of more than 90% under steady state conditions. GC/MS analysis confirms phosphorodithionicacid, O, O, S-trimethylester and diethylmercaptosuccinate as metabolites. Biodegradation of Malathion under inhibitory and non-inhibitory conditions was studied using Monod and Andrew-Haldane models and the kinetic constants were calculated and found to be mu(max): 0.271 per day; K-s: 126.3 mg/L using Monod and mu(max): 0.315 per day; K-s: 151.32 mg/L; K-i: 594.75 mg/L using Andrew-Haldane models. (C) 2016 Elsevier Ltd. All rights reserved.