A(2)BO(4) type oxides consisting of an alkali earth metal and tin showed high selectivity (> 99%) and activity for the oxidative coupling of methane at 1023 K in a methane-water redox system where active oxygen species ware regenerated by water. The products were C-2 hydrocarbons and hydrogen. Repeated reaction-oxidation cycles showed that the oxide is stable under both oxidative and reductive atmosphere. Doping of Bi to the oxide was found to enhance the activity for the oxidative coupling of methane.