A novel approach for high efficient conversion of the CO2-rich bio-syngas into the CO-rich bio-syngas was carried out by using biomass char and Ni/Al2O3 catalyst, which was successfully applied for production of bio-methanol from bio-oil. After the bio-syngas conditioning, the CO2/CO ratio prominently dropped from 6.33 to 0.01-0.28. The maximum CO yield in the bio-syngas conditioning process reached about 1.96 mol/(mol CO2) with a nearly complete conversion of CO2 (99.5%). The performance of bio-methanol synthesis was significantly improved via the conditioned bio-syngas, giving a maximum methanol yield of 1.32 kg/(kg(catalyst)) with a methanol selectivity of 99%. Main reaction paths involved in the bio-syngas conditioning process have been investigated in detail by using different model mixture gases and different carbon sources. (C) 2011 Elsevier Ltd. All rights reserved.