Hydrogen is a clean energy carrier, and its utilization will reduce environmental problems related to fossil fuels one. Biomass is an inexhaustible renewable source to generate bio-compounds. Glycerol, obtained from a crescent bio-diesel industry, is an abundant bio-substrate to produce hydrogen. The steam reforming of glycerol was studied employing 4Ni/Al2O3, 4Co-4Ni/Al2O3, and 12Co-4Ni/Al2O3 catalysts at 300, 500, and 700 degrees C, 1 atm, 10 h(-1) WHSV, 6:1 water:glycerol molar ratio (WGMR), 0.17 ml min(-1) glycerol solution feed flow rate and time-on-stream 8 h. The main product obtained was H-2, followed by CO2, CO, and CH4 in smaller proportion. Co promotes H-2 production and unfavors CO2 generation when temperature decreases; CH4 formation is observed at higher temperature. A low Co loading produces the largest H-2 and CO2 amounts at the lowest temperature. A high Co loading improves H-2 production at lower temperature, but this does not occur at high temperature. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.