The stability of Ni/gamma-Al2O3 catalyst in dry reforming of methane was found to be improved by the addition of MgO into the catalyst, probably due to the formation of out-layer MgAl2O4 spinels, which can effectively suppress the phase transformation to form NiAl2O4 spinel phases, stabilize the tiny Ni crystallites and suppress carbon deposition in dry reforming of methane.