An impregnation-precipitation method was developed for the preparation of activated carbon supported ruthenium-based catalysts for ammonia synthesis. The ammonia concentration in the outlet of reactor for the Ba-Ru-K/AC catalysts prepared via impregnation-precipitation method is as high as 20.4 vol% at 648 K, pressure of 10 MPa and with a space velocity of 10,000 h(-1), which is much higher than that of catalysts obtained via other preparation methods. The high performance of the catalyst is attributed to the efficient removal of chlorine ions and high dispersion of Ru nanoparticles, which is confirmed by element analysis, X-ray photoelectron spectroscopy, CO-chemsorption, and transmission electron microscopy. The present study provides a new concept for the preparation of carbon supported ruthenium based catalyst, which can be easily applied to industry and suitable for scale up production. (C) 2011 Elsevier B.V. All rights reserved.