Concs. of NOx, SOX and CO in flue gas from bituminous coal combustion were estd. by numerical simulation as a function of combustion temp., residence time and excess air ratio. The concn. of CO decreased with increasing combustion temp., residence time and air flux. The concn. of NO increased with increasing temp. and air flux and with decreasing residence time. The concn. of SO2 increased with increasing temp. and residence time and with decreasing air flux.