In the present study, wood biomass from Acacia mangium and its main components (hemicellulose (xylan), cellulose, and lignin) were blended with a sub-bituminous coal in 20:80 wt % ratio and subsequently were heat-treated at 900 degrees C using CO2 or N-2 atmospheres. The reactivity (ignition temperature and activation energy) under oxy-fuel conditions (21% O-2-79% CO2) was studied by thermogravimetry (TGA). It has been observed that adding biomass or its main components to coal improved the combustion efficiency. Coal/biomass and coal/xylan/cellulose/lignin char blends showed lower ignition temperatures when they were devolatilized using CO2 instead of N-2. In addition, the activation energies were lower for blends thermally treated with CO2. Differences in reactivity are discussed considering changes in physical-chemical properties characterized by SEM, N-2 adsorption at -196 degrees C, Raman spectroscopy, and XPS.