Biomass is a renewable alternative to fossil raw materials in the production of liquid fuels and chemicals. Pyrolyzed biomass derived liquids contain oxygenated molecules that need to be removed to improve the stability of these liquids. A hydrotreating process, hydrodeoxygenation (HDO), is commonly used for this purpose. Thus, the aim of this work is to examine the role of advanced NiMo and NiW catalysts developed for HDS purposes in a HDO reaction. In addition, product distribution and catalyst stability are studied against changes in the feed composition, the solvent, and the catalyst pretreatment. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.