In this work, ZrO2 was employed as support and as Al2O3 modifier of Ni based catalysts due to its special interesting characteristics. The catalytic activity of these systems was studied in steam reforming of glycerol to produce H-2. As the activity results at 773 K and 873 K showed, the NiZ catalyst allowed low glycerol conversion and H-2 production when compared to the Ni gamma A catalyst. Moreover, the NiZ catalyst was not able to reform intermediate liquid products into gaseous products. The behaviour of the Ni gamma A catalyst was improved when an intermediate content of ZrO2 was added to Al2O3, resulting in higher H-2' yield and capacity to reform intermediate products even at 773 K. This improvement seems to be related to a larger proportion of surface Ni species (XPS). This Ni-o proportion increase could be attributed to the formation of ZrO2-Al2O3 species. These species decreased Ni2+ species reduction temperature, favouring Ni2+ -> Ni-o transformation. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.