Biomass char, obtained from the residues of biomass pyrolysis, was employed as feedstock for the gasification using an air-steam agent. The gasification with the energy self-sufficiency was carried out in a cyclone furnace where combustor and gasifier were combined into one reactor. The effects of equivalence ratio (ER) and steam to char ratio (S/C) on gasification performance were investigated. The results showed that the increasing ER led to the increasing reactor temperature and increased dry gas yield, H(2) yield and carbon conversion efficiency. The introduction of steam promoted the gas quality, but excessive steam would lower reactor temperature and degrade gas quality. Under the optimum experimental conditions (ER = 0.36, S/C = 0.45), the yield of the tar-free gas reached 3.72 N m(3)/kg and the LHV of the fuel gas was 4163 kJ/N m(3). (C) 2011 Elsevier Ltd. All rights reserved.