Abstract: Various physico-chemical properties of high strength spherical catalyst A110-5Q, i. e., the densities, porosity, void fraction, specific pore volume, crushing strength and Mossbauer spectroscopy in the oxidized state, and the porosity, specific pore volume, specific surface area, average pore radius, pore size distribution, catalytic activity and kinetic parameters in the reduced state have been studied. In the oxidized state the crystal grains of the high strength catalyst with pore size of-1000A are packed more closely and the bulk and particle densities are 10-12% higher than those of the low strength catalyst with pore size of 1-5μm. In the reduced state the average pore radius and the most probable pore radius in the high strength catalyst are larger than those in the low strength catalyst, and there are three systems of pores in the former. Besides a twofold increase of the crushin gstrength, the high strength catalyst still maintaisn high activity and low flow resistance. The values of freuqency factor(ko)and activation energy(E) for ammonia synthesis are higher than those of the low strength spherical catalyst and the compensation effect equation, lnko = B+ f·E, applies.