A metal oxide catalyst capable of catalyzing an oxidative coupling of methane reaction is described. The metal oxide catalyst includes a lanthanum (La) cerium (Ce) metal oxide and further including a lanthanum hydroxide (La(OH)3) crystalline phase. The catalyst is capable of catalyzing the production of C2+ hydrocarbons from methane and oxygen. Methods and systems of using the metal oxide catalyst to produce C2+ hydrocarbons from a reactant gas are also described.