The ammonia synthesis was performed over Ru catalyst supported on perovskite-type BaZrO3. Physiochemical properties of this catalyst were also characterized by means of various techniques to show the relationships between catalyst structure and catalytic performance. It was found that the ammonia concentration in the effluent of Ru/BaZrO3 catalyst was 6.36% at 673 K under 3.0 MPa, which was much higher than that of Ru catalyst supported on other supports including carbon material systems under the similar conditions, and the rate did not decrease even if the reaction was executed for 120 h. This might be attributed to the facts that the optimum size of Ru particles has more B-5-type sites, strong electron-donating ability of the BaZrO3 support and the strong metal-support interaction provides an efficient channel for electron transfer. On the other hand, the adsorption of H-2 was inhibited over the surface of this catalyst and the number of active sites for the activation of N-2 was also increased. (c) 2013 Elsevier B.V. All rights reserved.