The catalytic properties for the oxidative coupling of methane (OCM) of La0.8Sr0.2CoO3 (LSC) and SrCo0.8Fe0.2O3 (SCF) in solid solution were studied and compared with those of 5 wt% Li/MgO, using a steady/unsteady state packed-bed reactor and a transient microbalance. The results of the steady-state cofeed experiments show that LSC possesses OCM catalytic properties similar to those of Li/MgO in terms of C-2 yield and selectivity at temperatures of around 800 degrees C, The former gives a larger C-2 space time yield than the latter, SCF exhibits poor OCM catalytic properties at 700-850 degrees C. To further examine the suitability of LSC as a membrane material for use in a dense membrane reactor for OCM, the instant OCM selectivity and activity and oxygen consumption rate for LSC and 5% Li/MgO on exposure to pure methane in cyclic feed mode were measured respectively at 850 degrees C and 800 degrees C, For both materials, the unsteady-state cyclic feed operation gives smaller initial OCM activity and larger initial C-2 selectivity than the cofeed steady state operation. Li/MgO quickly loses its OCM activity and selectivity in the unsteady state operation due to rapid consumption of the active sites, Up to 5 min of methane run time, LSC maintains appreciable OCM activity with poorer C-2 selectivity as compared to the steady state cofeed operation. The surface of LSC membrane at low oxygen partial pressure may become nonselective for OCM in membrane reactor applications.