In this work, thermal behavior and gas emission characteristics of coal, different kinds of biomass chars, and their blends were evaluated by using the thermogravimetric analyzer coupled with a mass spectroscope. The chars were prepared from wheat straw at 300 degrees C and 500 degrees C under N-2 and CO2 atmosphere, respectively. The results show that the pyrolysis temperature has a greater effect on the combustion characteristics of biomass char than the pyrolysis atmosphere. NOx emissions were reduced effectively with the addition of biomass chars. The study also reveals that there is an obvious improvement in the combustion behavior of coal when blended with biomass chars.