CeO2-BaCeO3,　Ce0.8Gd0.2O1.9　(GDC)-BaCeO3,　CeO2-BaCe0.8Y0.2O3-δ　(BCY)　and　GDC-BCY　composite　powders　(in　a　molar　ratio　1:1)　were　prepared　via　a　sol-gel　combustion　method　and　a　mechanically-mixing　method.　The　effect　of　doping　elements　on　the　solid-state　reaction　between　doped　CeO2　and　doped　BaCeO3　at　a　sintering　temperature　of　1　550℃　was　investigated.　The　electrochemical　properties　of　GDC-BCY　composite　electrolyte　were　investigated.　The　results　show　that　the　doping　of　elements　into　CeO2-BaCeO3　suppresses　the　evaporation　of　BaO,　and　promotes　the　solid-state　reaction　between　GDC　and　BCY.　The　GDC-BCY　composite　electrolyte　sintered　at　1　550℃　produces　a　perovskite　phase　of　BaCe1-x-yGdxYyO3-α.　The　conductivity　of　the　GDC-BCY　pellet　after　solid-state　reaction　is　much　greater　than　that　of　the　single　phase　BCY,　and　slightly　smaller　than　that　of　the　single　phase　GDC.　The　single　cell　with　GDC-BCY　composite　electrolyte　has　a　peak　power　density　of　0.657　W/cm2　at　700℃,　which　is　greater　than　that　of　the　cells　with　the　GDC　or　BCY　electrolyte.　©,　2015,　Kuei　Suan　Jen　Hsueh　Pao/Journal　of　the　Chinese　Ceramic　Society.　All　right　reserved.