A combined unit of biomass gasifier and tar steam reformer (CGR) was proposed in this study to achieve simultaneous tar removal and increased hydrogen production. Tar steam reforming calculations based on thermodynamic equilibrium were carried out by using Aspen Plus software. Thermodynamic analysis reveals that when selecting appropriate operating conditions, exothermic heat available from the gasifier could sufficiently supply to the heat-demanding units including feed preheaters, steam generator and reformer. The effects of gasification temperature (T-gs), reforming temperature (T-ref) and steam-to-biomass ratio (S:BM) on percentages of tar removal and improvement of H-2 production were investigated. It was reported that the CGR system can completely remove tar and increase H-2 production (1.6 times) under thermally self-sufficient condition. The increase of H-2 production is mainly via the water-gas shift reaction. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.