Al(2)O(3)-Supported Co, Cu, Cr, Fe, Mn, Ni and V oxide catalysts were prepd. by impregnation of the substrate and used for oxidn. of NH(3) to N(2) with O(2)/He mixt. at 100-400 degrees C. For comparison, the corn. MnO(2)/CuO hopcalite catalyst was used after calcination at 300-500 degrees C. The Cr, Co, Mn and Cu oxide catalysts showed high catalytic activity but only the CuO catalyst was highly selective. The hopcalite catalysts gave N oxides as main products at full NH(3) conversion.