Catalyzing cations Cu2+, Mg2+, Na+, NH4+ and their mixt. were added (300 ppm) to a coal fuel studied then for combustion ability under lab. conditions at const. fuel and air supply rate. The concns. of O-2, CO, CO2, SO2 and NOx in flue gases were detd. The most effective in reducing CO emission (approx. 10%) was the Cu-contg. catalyst and in reducing NOx emission (approx. 6%) the NH4-contg. when compared to the fuel without any additives. Use the mixed catalyst resulted in decreasing the emissions of CO and NOx by 6% and 12%, resp.