Fused Fe-Co catalysts, with various cobalt contents, were obtained by melting of oxides of these metals and oxides of promoters at the temperature of 1600 degrees C. The determination of the chemical composition was based on the ICP-OES method. It followed from the XRD phase analysis that cobalt had been built-in in the iron oxides lattice. Catalysts' activities in the ammonia decomposition reaction, in temperatures within 475-600 degrees C, for ammonia concentration at the reactor inlet between 0.5 and 100%vol, and under atmospheric pressure, were investigated. Almost full ammonia decomposition was reached at 600 degrees C for ammonia mole fraction in the range from 0.1 to 0.25 at GHSV = 24,000 cm(3) g(-1) h(-1). The rate of the ammonia decomposition depends on a nitriding potential. The maximal value of the ammonia decomposition rate was reached at ln P = -6.5 for FeCo(18.3) catalyst, and at ln P = -5.8 for the FeCo(4.8) catalyst. The catalyst with higher content of promoters showed higher activity in the ammonia decomposition reaction. (C) 2013 Elsevier B. V. All rights reserved.