Dry reforming of methane to synthesis gas was studied over Ni-based catalysts. Compared to Ni/gamma-Al2O3, the Ni/MgO-gamma-Al2O3 and Ni/MgAl2O4 catalysts exhibit higher activity and better stability using a stoichiometric feed ratio (1:1). The MgAl2O4 spinel layer in Ni/MgO-gamma-Al2O3 can effectively suppress the phase transformation to form NiAl2O4 spinel phases and can stabilize the Ni tiny crystallites, to which the good stability of the catalyst contributes. The application of magnesium aluminate spinel (MgAl2O4) prepared by the co-precipitation method as a support of Ni catalysts can give a high active catalytic system with excellent stability under reaction conditions. The high sintering-resistance ability and low acidity of MgAl2O4 compared to gamma-Al2O3 and the interactions between Ni and MgAl2O4 might be responsible for its high activity and resistant to coking and sintering, because it can produce a highly dispersed active Ni species. (C) 2004 Elsevier B.V. All rights reserved.