Hydrodeoxygenated pyrolysis-oils (HDO-oil) are considered promising renewable liquid energy carriers. As such, it cannot be applied in in-stationary combustion engines so more "upgrading" is required. A considerable alternative is to co-process HDO-oil along with vacuum gas oil (VGO) in a Fluid Catalytic Cracking unit (FCC). This study evaluates the impact of adding 20 wt.% HDO-oil to a conventional FCC feed-stock. The VG and bio-oil mixtures were co-injected into a fixed-bed reactor simulating FCC conditions using an equilibrated industrial FCC catalyst. Co-processing of 20 wt.% HDO-oil with VGO gave comparable yields for the gasoline fraction to that of the pure VG cracking. However, during co-processing oxygen removal from HDO-oil oxygenated components consumes hydrogen coming from the hydrocarbon feedstock. As a result the final product composition is poor in hydrogen and contains more coke, aromatics and olefins. (C) 2010 Elsevier B.V. All rights reserved.