Addition　of　doped　ceria　to　double　perovskite　oxide　such　as　PrBa0.8Ca0.2Co2O5+delta(PBCC)　leads　to　remarkable　performance　enhancement　of　solid　oxide　fuel　cells　(SOFCs),　however,　the　challenge　is　to　facilely　fabricate　nano-structured　PBCC　cathodes　with　nanoscale　doped　ceria　without　agglomeration　of　the　ultrafine　phase　during　the　conventional　high　temperature　electrode　sintering　process.　Here,　we　report　the　fabrication　of　an　ultrafine　PBCC-Gd0.2Ce0.8O1.9　(GDC)　composite　via　a　facile　co-synthesis　route　and　direct　assembly　approach　without　the　high　temperature　sintering　process.　The　as-fabricated　PBCC-GDC　composite　powder　calcined　at　750　degrees　C　contains　PBCC,　GDC,　BaCoO3-delta(BCO)　and　PrCoO3-delta(PCO),　and　only　PBCC　and　GDC　phases　as　the　calcination　temperature　increases　to　850　degrees　C　and　higher.　A　single　cell　with　the　directly　assembled　multi-phased　PBCC-GDC　powder　calcined　at　750　degrees　C　exhibits　a　peak　power　density　of　2.08　W　cm(-2)　at　an　operating　temperature　of　750　degrees　C,　and　is　stable　at　0.5　A　cm(-2)　and　700　degrees　C　for　over　100　h.　The　outstanding　electrode　performance　and　stability　is　primarily　ascribed　to　the　in　situ　formation　of　intimate　electrode/electrolyte　interface　by　polarization　and　the　construction　and　retaining　of　ultrafine　electrode　microstructure.　This　work　shed　lights　onto　the　development　of　a　facile　strategy　to　prepare　highly　active　and　stable　double　perovskite　based　composite　cathode　for　SOFCs.　(C)　2021　Elsevier　Ltd.　All　rights　reserved.