A cobalt catalyst precursor for the ammonia decomposition, in the form of cobalt oxide (II and III) promoted with oxides of calcium, aluminum, and potassium, was obtained by precipitation method. The increase in the precipitation process temperature reduces the average size of Co3O4 crystallites obtained in the calcination process. The addition of alumina has a positive effect on the area of the active surface, surface stability and catalytic activity of the active form of the catalyst, namely metallic cobalt, in the ammonia decomposition reaction. The highest activity was achieved for the catalyst ZBAP1-C promoted with oxides of calcium, aluminum, and potassium, which attained the ammonia decomposition degree of approximately 100% at a temperature of 525 degrees C. There were no changes observed in the crystalline structure of the ZBAP1-C catalyst during the "in situ" XRD studies of the ammonia decomposition at a temperature of 475 degrees C when the nitriding potential changed. (C) 2016 Elsevier B.V. All rights reserved.