The catalytic performance of nickel–magnesia catalysts in CO2 reforming of methane and the factors influencing carbon deposition during the reaction were investigated by a comparative study of different reduced NixMg1−xO solid solution catalysts. With the characterization results of X-ray diffraction (XRD), BET surface area, scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA) it was found that the excellent anti-coking performance of reduced solid solution catalyst with low Ni content is attributable to high dispersion of reduced Ni species, basicity of support surface and nickel–support interaction.