A series of cogasification experiments were performed at a 100 kW bubbling fluidized bed (BFB) gasifier to gasify the blended pellets made from two types of coals and woody biomass, with biomass-to-fuel mass ratios of 0-30%. In the cogasification, a mixture of air and steam was fed from the BFB gasifier bottom as gasification agent and the blended biomass-coal pellets were fed into the bed layer. Impacts of biomass mass fraction in the binary pellets and gasification operation temperature on producer gas composition were experimentally investigated. The experimental results have been used to validate a mathematical model developed in this study. From both experimental observation and model prediction, it was found that adding biomass into coal has overall negative impact on producer gas quality in terms of combustible substance contents, and the extents of the blending effect were different among fuel types which have different properties. (c) 2015 American Institute of Chemical Engineers AIChE J, 61: 1639-1647, 2015