The aim of this work is to study the catalytic activity of Ni(10%) based catalysts supported over (a) over tilde -Al2O3 modified with Mg (3%) for the steam reforming of glycerol. Catalysts have been prepared by incipient wetness impregnation method; analysing the effect of the calcination temperature of the modified support and the calcination temperature of the catalysts. Catalysts were characterized by temperature programmed reduction, (TPR), x-ray diffraction (DRX) and BET surface area. All catalysts were tested for this reaction in a fixed bed reactor. The best performance was achieved with the catalyst calcined at 500 degrees C being the optimum calcination temperature for the modified support of 900 degrees C This behaviour is ascribable to the formation of MgAl2O4 spinel which favours the dispersion of Ni degrees, responsible of the catalytic activity. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.