The addition of Y2O3 to Ni/alpha-Al2O3 catalysts was investigated by BET surface area measurements, hydrogen chemisorption, X-ray diffraction, UV-vis diffuse reflectance spectroscopy, X-ray fluorescence, temperature programmed reduction, temperature programmed oxidation and cyclohexane dehydrogenation. Autothermal reforming experiments were performed in order to evaluate the methane conversion and proceeded through an indirect mechanism consisting of total combustion of methane followed by CO2 and steam reforming generating the synthesis gas. The Y2O3 center dot Al2O3 supported catalysts presented better activity and stability in autothermal reforming reaction. Temperature programmed oxidation analysis demonstrated that the addition of Y2O3 resulted in a change of the type or the location of coke formed during reaction. None of the prepared catalyst presented deactivation by sintering under the tested conditions. The improved stability of supported catalysts Y2O3 center dot Al2O3 was the result of minimizing the formation of coke on the surface of nickel particles. (C) 2009 Elsevier B.V. All rights reserved.