Methane could be converted to higher hydrocarbons by the two-step reaction using supported metal catalysts. At the first stage methane contacted with metal surface to produce carbonaceous species and hydrogen. Carbonaceous species then reacted with hydrogen to produce higher hydrocarbons at the second stage. Experiments were carried out with aluminasupported ruthenium or platinum catalysts using a quartz tubular reactor. The reaction mixtures were analyzed with a mass spectrometer and a gas chromatograph. The catalyst with too high hydrogenolysis activity produced mostly methane in the second-stage hydrogenation reaction, resulting in the low selectivity toward higher hydrocarbons. When the catalytic activity for the hydrogenolysis reaction was too low, both the selectivity of higher hydrocarbons and the reaction rate were low. Thus, it was concluded that the metal catalyst should have the moderate catalytic activity toward the hydrogenolysis reaction for the maximum conversion of methane to higher hydrocarbons. Supported platinum catalysts exhibited the lower hydrogenolysis activity than the supported ruthenium catalyst, producing larger amounts of higher hydrocarbons. Among supported platinum catalysts, the 5% platinum supported on alumina catalyst, having the moderate hydrogenolysis activity, was superior to the 0.5% Pt supported catalyst. The optimum temperature for the adsorption of methane on metal surface was about 250 ℃. The noble metal catalysts tested in this work can also be applied to the process of producing hydrogen by direct decomposion of methane.