In the present paper, the study focuses on the effects of sodium dodecyl sulfate (SDS) surfactant on the release of extracellular polymeric substance (EPS) followed by pretreatment with a thermophilic protease-secreting bacterial strain on WAS (waste activated sludge). This in turn enhanced the subsequent anaerobic biodegradability. The extracellular polymeric substances were released using SDS (0.03 g/g SS of dosage) to stimulate the bacterial pretreatment. The thermophilic bacterial pretreatment results indicated that deflocculated (EPS released with SDS and pretreated with bacteria) sludge showed higher Suspended Solids (SS) reduction of about 27% and Chemical Oxygen Demand (COD) solubilization of about 24%, whereas flocculated (pretreated with bacteria alone) showed SS reduction of about 18% and COD solubilization of about 16%. The biogas production potential of deflocculated, flocculated, and raw (untreated) samples was found to be 2.5211 L/(gVS), 1.7677 L/(gVS), and 0.6140 L/(gVS), respectively. As a result, the EPS release followed by disintegration of sludge by bacteria enhanced the biogas production. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.