Partial oxidation of methane (POM) was systematically investigated in a fixed bed reactor over 12 wt% Ni catalysts supported on α-Al2O3, γ-Al2O3 and θ-Al2O3 which were prepared at different conditions. Results indicate that the catalytic activity toward POM strongly depends on the BET surface area of the support. All the Ni/θ-Al2O3 catalysts showed high activity toward POM due to the less formation of inactive NiAl2O4 species, the existence of NiOx species and stable θ-Al2O3 phase. Although Ni/γ-Al2O3 showed the highest activity toward POM, long-time stability cannot be expected as a result of the deterioration of the support at higher temperature, which is revealed from BET results. From the reaction and characterization results, it is inferred that the optimal conditions for the preparation of θ-Al2O3 are 1,173 K and 12 h.