A combustion model for wheat straw is discussed and compared to that of a bituminous coal, Pittsburgh No. 8. The input data into the combustion model for both cases were generated using the FG-DVC pyrolysis model, which had been validated in part experimentally. The combustion behaviour of the two fuels are investigated using a laminar flow CFD model of a drop-tube furnace. The results indicate that, because of the low calorific nature of the straw volatiles, the combustion takes place at a lower temperature, but with rapid ignition and rapid devolatilisation. The straw char is highly microporous with relatively high ash and oxygen contents; consequently, the burnout is quicker than the analogous coal char burnout.