Small amounts Sn doped Ni catalysts exhibited excellent coke resistance ability with minor loss of reforming activity in CH4 reforming with CO2. Temperature-programmed reduction with H-2 (H-2-TPR) showed that the addition of Sn increased the reducibility of Ni. X-ray photoelectron spectroscopy (XPS) analysis of Ni/alpha-Al2O3 (I), Sn0.02Ni/alpha-Al2O3 (II), indicated that the binding energy of the Ni 2p level was decreased from 855.7 (I) to 855.2 eV (II) by the addition of Sn. Field emission scanning electron microscopy (FE-SEM) and field emission transmission electron microscopy (FE-TEM) analysis of the fresh and used catalysts (I, II) revealed that the added Sn increased the dispersion of Ni and retarded sintering of Ni. XPS and EDX also disclosed that Sn was aggregated on the surface of Ni, and the coverage of Sn on the surface of Ni depressed the reforming activity. (C) 2004 Elsevier B.V. All rights reserved.