The effects of MgO loading and calcination temperature of the catalysts on the carbon dioxide reforming of methane (CDR) have been extensively investigated over Ni/MgO/Al₂O₃ catalysts in a fixed-bed reactor system. Results indicate that the activity and stability of the catalysts were significantly influenced by both MgO loading and calcination, temperature, i.e., higher calcination temperature and higher MgO loading are essential for high activity and stability of the catalyst. Characterization results indicate that mixed spinel phase composed of MgAl₂O₄ and NiAl₂O₄ is effective to produce active and stable Ni species having strong Ni to support interaction resulting in active and stable catalytic performance in CDR.