A method is provided for removing tar from a gas by contacting a first gas containing tar with a second gas containing oxygen for time period sufficient to effect oxidation of at least a portion of the tar in the first gas, thus producing an oxidized product gas that contains less tar than the first gas. The method can also include heating a fluidized particulate material in a combustor, introducing the heated fluidized particulate material from the combustor and a biomass feedstock into a gasifier, such that heat from the heated fluidized particulate material causes the gasification of at least a portion of the biomass feedstock to form a tar-containing product gas, the first gas may contain at least a portion of the tar-containing gas, and the tar-containing gas may be extracted from the gasifier prior to contacting the first gas with the second gas.