The　Ce0.8Sm0.2O1.9-BaCe0.8Sm0.2O2.9　(SDC-BCS,　molar　ratio　1:1)　composite　electrolytes　were　prepared　via　mechanically-mixing　method　and　one-step　citric　acid-nitrate　gel　combustion　method.　The　SDC-BCS　pellets　were　sintered　in　air　at　1550　for　5　h.　The　microstructure　and　electrochemical　properties　of　SDC-BCS　composite　electrolyte　prepared　by　different　methods　were　investigated.　The　results　show　that　phase　distribution　of　SDC-BCS　composite　electrolyte　via　one-step　method　is　more　uniform　than　that　of　mechanically-mixing　method.　The　phase　boundary　of　SDC-BCS　composite　can　provide　the　transfer　channel　for　protons　and　oxygen　ions,　which　is　benefit　to　the　improvement　of　the　grain-boundary　conductivity.　The　open　circuit　voltage　and　the　peak　power　density　of　the　single　cell　with　SDC-BCS　composite　electrolyte　via　one-step　method　are　higher　than　that　of　SDC-BCS　composite　electrolyte　via　mechanically-mixing　method.　©　2016,　Editorial　Department　of　Journal　of　the　Chinese　Ceramic　Society.　All　right　reserved.