Catalytic performance of Na2CO3-K2CO3 and Li2CO3-K2CO3 immobilized on lithium aluminate towards the oxidative dimerization of methane was investigated at 750, 800 and 850-degrees-C. CH4 conversion of 15-16%, C-2 yield of 9-10%, and C-2 selectivity if 58-62% was obtained at 800-degrees-C. Catalytic activity increased with temperature and melt decarbonation, which can be correlated with a stabilization of peroxide species. Comparison between these melts and with Li2CO3-Na2CO3 shows that a higher amount of C-2 hydrocarbons, formed per second and per gram of carbonate, was obtained in Li2CO3-K2CO3.