A Box-Behnken design of response surface methodology (RSM) was applied to examine the glycerol steam reforming over Ni/Al2O3 nanocatalysts. The catalysts were synthesized by impregnation method and characterized by XRD, BET, and TPR techniques. The results of XRD analysis revealed the crystalline sizes of 5.1 nm and 17.2 nm for the Al2O3 and 15 wt % Ni/Al2O3 catalyst, respectively. The effects of the process independent variables namely gas hourly space velocity (GHSV), temperature (degrees C) and feed ratio (water to glycerol ratio) on glycerol conversion to gaseous products (H-2, CH4, CO2 and CO) were investigated and 3D surface plots were obtained in order to visualize the interactive effects of variables. For most of the responses, experimental results showed the adequately of fitted data into first and second-order polynomial models. Ultimately the process was optimized and the optimum conditions for the glycerol steam reforming were: GHSV (36,787 mL g(-1) h(-1)), temperature (671.8 degrees C) and feed ratio (9). At the optimized conditions glycerol conversion, H-2, CH4, CO2 and CO production were found to be 97.53%, 74.40%, 0.15%, 23.87% and 1.55%, respectively. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.