The　high　reactivity　between　bismuth　oxide　and　cobaltite　oxygen　electrodes　is　a　bottleneck　in　developing　active　and　reliable　bismuth　oxide-cobaltite　composite　oxygen　electrodes　for　solid　oxide　cells　(SOCs).　Herein,　a　Sr-free　Sm0.95Co0.95Pd0.05O3-δ　(SmCPd)　oxygen　electrode　decorated　with　nanoscale　Er0.4Bi1.6O3　(ESB)　is　synthesized　and　assembled　on　a　barrier-layer-free　Y2O3-ZrO2　(YSZ)　electrolyte　film.　The　cell　with　the　ESB　decorated　SmCPd　composite　oxygen　electrode　exhibits　a　peak　power　density　of　1.81　W　cm-2　at　750　°C　and　0.58　W　cm-2　at　650　°C.　More　importantly,　excellent　operating　stability　is　achieved　in　the　fuel　cell　mode　at　600　°C　for　500　h,　and　in　electrolysis　and　reversible　modes　at　750　°C　for　over　200　h.　The　results　demonstrate　the　feasibility　of　applying　bismuth　oxide-cobaltite　composite　oxygen　electrodes　in　developing　high-performance　and　durable　SOCs.　©　2018　The　Royal　Society　of　Chemistry.