Dense membranes of mixed-conducting perovskite-type oxides La0.6Sr0.4,CO0.8Fe0.2O3 and La0.8Ba0.2Co0.8Fe0.2O3 were used for methane coupling by application of pressure-driven O2 permeation. High operating temperatures, typically above 800°C, were needed to obtain reasonable oxygen fluxes. Conversions were small (1–3%). Both compositions showed comparable C2 selectivities at low methane partial pressures. At higher pressures the selectivity to C2 hydrocarbons for La0.6Sr0.4CO0.8Fe0.2O3 increased to 67%, whereas La0.8Ba0.2CO0.8Fe0.2O3 showed small C2 selectivities. Strong surface segregation of Sr and Ba was shown by SEM for both compositions.