Autothermal reforming, which is a combined process of steam reforming and partial oxidation reforming, has excellent coke resistance and high efficiency in reforming reactions. Octane autothermal reforming was carried out over Ni-supported catalysts. The catalysts were prepared by normal precipitation and promoters were added by impregnation. The formation of NiO-MgO solid solution was accomplished during calcination of the Ni/MgO catalyst at 900 degrees C, resulting in loss of the active Ni metal and very low catalytic activity. Therefore, all catalysts were treated by a reduction process without calcination in order to prevent the formation of NiO-MgO solid solution. Among Ni/MgO catalysts combined with various promoters such as Ag, Cr, and Cu, Ni-Cr/MgO catalyst showed the most desirable characteristics in the aspects of its activity, stability, and resistance to carbon deposition. We found an optimal condition for octane autothermal reforming when steam-to-carbon ratio and oxygen-to-carbon ratio were 1.5 and 0.5, respectively. (C) 2010 Elsevier B.V. All rights reserved.