New forms of energy production, such as combined-cycle power plants and fuel cells, can be introduced by gasification. When gasifying nitrogenous fuels, organic and inorganic nitrogen compounds form in the gas. In gas combustion these can form nitrogen oxides detrimental to the environment. Catalytic decomposition of the nitrogen compounds in the gasification gas is one alternative for reducing the formation of nitrogen oxides. In the research work under review, catalytic effects of various inexpensive materials on the nitrogen compounds of the gasification gas at high temperatures were studied. The materials were iron sinter, iron pellet, ferrous dolomite, dolomite and limestone, and, as reference materials, inert silicon carbide and a commercial nickel catalyst. The most significant nitrogen compounds formed in gasification are ammonia, hydrogen cyanide and organic nitrogen compounds of tar. The ferrous materials and the commercial nickel catalyst proved to be the most efficient agents for decomposing ammonia. Limestone and dolomite did not exhibit any essential catalytic capacity for decomposing ammonia, although they reduced the hydrogen cyanide content of the gas.