Controlling triple phase boundary (TPB), an intersection of the ionic conductor, electronic conductor and gas phase as a major reaction site, is a key to improve cell performances for low-temperature solid oxide fuel cells. We report a synthesis of morphologically well-defined Gd0.1Ce0.9O1.95 (GDC) embedded Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) nanofibers and their electrochemical performances as a cathode. Electrospun fibers prepared with a polymeric solution that contains crystalline Ba0.5Sr0.5Co0.8Fe0.2O3-delta particles in similar to 200 nm size and Gd(NO3)(3)/Ce(NO3)(3) precursors in an optimized weight ratio of 3 to 2 result in one dimensional structure without severe agglomeration and morphological collapse even after a high calcination at 1000 degrees C. As-prepared nanofibers have fast electron pathways along the axial direction of fibers, a higher surface area of 7.5 m(2) g(-1), and more oxygen reaction sites at TPBs than those of GDC/BSCF composite particles and core-shell nanofibers. As a result, the Gd0.1Ce0.9O1.95 embedded Ba0.5Sr0.5Co0.8Fe0.2O3-delta nanofiber cell shows excellent performances of the maximum power density of 0.65 W cm(-2) at 550 degrees C and 1.02 W cm(-2) at 600 degrees C, respectively.