Aqueous-phase reforming (APR) of sorghum hydrolyzate was performed in a fixed bed reactor applying response surface methodology (RSM) based on the Box-Behnken design (BBD) to produce hydrogen gas. The results showed that RSM based on the BBD was a well-matched method for optimizing of APR of sorghum hydrolyzate. The independent variables such as interactive effects of temperature, feed flow rate, and carbon content of sorghum hydrolyzate on the APR were investigated. The mathematical model and experimental results showed that the operation temperature was the main positive linear effect whereas the interaction between temperature and feed flow rate was the main negative linear effect on the hydrogen yield. The highest hydrogen production was found to be a temperature of 270 degrees C, a hydrolyzate flow rate of 0.30 mL/min, and a carbon content of biomass concentration of 2500 mg/L. The highest H-2/CO2 mole ratio (7.9) obtained at 270 degrees C when carbon content of sorghum hydrolyzate was 1000 mg/L. 2013 Elsevier Ltd. All rights reserved.