The hetero-homogeneous processes, especially, the oxidations ofmethane, ethane and ethylene in gas-phase and in the presence of catalystswere studied. The main factors in oxidative coupling of methane were classi-fied into two types according to their effects on the reactions. The inherent lim-it of the C_2 yield was discussed from the reaction condition point of view. Aview toward the inherent limit, i. e., a way to avoid the inherent limit by oper-ating at high selectivity, high C_2 concentration, efficient product separation andmethane circulating operation, was proposed. The methods to enhance theC_2 selectivity and the C_2 concentration in the exit gas, and the method for effi-cient product separation were investigated. In the simulation experiment a prod-uct gas with C_2 concentration of 90 (v/v)％, and C_2 selectivity of 85％ (basedon carbon number), was produced under the reaction conditions of 10(at)％~La_2O_3/SrO catalyst, T=800℃, τ=0.012g·s·cm~(-3), P_(CH_4)/Po_2=9, Po_2=10kPa and atmospheric pressure. The hetero-homogeneous processes, especially, the oxidations of methane, ethane and ethylene in gas-phase and in the presence of catalysts were studied. The main factors in oxidative coupling of methane were classi-fied into two types according to their effects on the reactions. The inherent lim-it of the reaction limit point of view. Aview toward the inherent limit, ie, a way to avoid the inherent limit by oper-ating at high selectivity, high C_2 concentration, efficient product separation and methane circulating operation, was proposed. The methods to enhance the C 2 selectivity and the C 2 concentration in the exit gas, and the method for effi-cient product separation were investigated. In the simulation experiment a prod-uct gas with C_2 concentration of 90 (v / (at%) ~ La 2 O 3 / SrO catalyst, T = 800 ° C., τ = 0.012 g · s · cm -1, and C 2 selectivity of 85% 3), P_ (CH_4) / Po_2 = 9, Po_2 = 10kPa and atmospheric pressure.