In this paper, the gaseous nitriding at lower temperature and nitriding mechanism from a surface catalysis were studied. Alloy cast iron supported by catalysts on its surface were prepared by alternating currents precipitation way (ACPW) which generates the catalytic surface. The subsequent catalytic decomposition of ammonia and surface adsorption of the free nitrogen were greatly enhanced by the catalysts on its surface. Hence, the nitriding kinetics was improved from 360 degrees C to 500 inverted perpendicular C, and the diffusion activation energy of nitrogen atom was decreased. These works not only study the surface catalysis nitriding mechanism, but also solves the problems in nitriding process. This work widens the field of surface catalysis application. (C) 2010 Elsevier B.V. All rights reserved.