Oxidative coupling of methane to ethylene is of high importance to the future of light olefin industry.However,the carbon atom efficiency is normally below 50％ in gas phase reaction which is limited to the overoxidation of methane to carbon dioxide with oxidants.Here we present an alternative approach of electrochemical oxidation of methane in an oxygen permeation membrane reactor and show the highest conversion of methane and C2 selectivity of 28％ and 40.2％ at 1150 ℃,respectively.We prepare the 100-μm-thick perovskite(La0.8Sr0.2)1-xCr0.5Fe0.5O3-δ,(LSCrF)dense membrane supported on the 500-μm-thick porous(La0.8Sr0.2)1-xCr0.5Fe0.5O3-δ(LSCrF-Fe)(x = 0,0.02,0.05 and 0.10)scaffolds while the excess of Fe would be exsolved on porous skeleton to create metal-oxide interfaces toward methane oxidation.The metal-oxide interfaces not only facilitate the activation of C-H bond in methane but also enhance the coking resistance.