Sago wastewater (SWW) causes pollution to the environment due to its high organic content. Annually, about 2.5 million tons of SWW is produced in Malaysia. In this study, the potential of SWW as a substrate for biohydrogen production by Enterobacter aerogenes (E. aerogenes) was evaluated. Response Surface Methodology (RSM) was employed to find the optimum conditions. From preliminary optimization, it was found that the most significant factors were yeast extract, temperature, and inoculum size. According to Face Centered Central Composite Design (FCCCD), the maximum hydrogen concentration and yield were 630.67 mu mol/L and 7.42 mmol H-2/mol glucose, respectively, which is obtained from the sample supplemented with 4.8 g/L yeast extract concentration, 5% inoculum, and incubated at the temperature of 31 degrees C. Cumulative hydrogen production curve fitted by the modified Gompertz equation suggested that H-max, R-max, and lambda from this study were 15.10 mL, 2.18 mL/h, and 9.84 h, respectively. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.