Fibrous perovskite oxide has been the most promising cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs) due to its efficient mass and charge transfer. Herein, a core-shell fiber-structured YCo0.5Fe0.5O3 (YCF)- Gd0.1Ce0.9O1.95 (GDC) cathode is synthesized via the modified electrospinning technique. These unique YCF-GDC fibers exhibit a uniform diameter of 300 nm, and the GDC particles are attached to the YCF fiber cores. The electrochemical performance demonstrates a relatively low area-specific resistance of 0.66 Omega.cm(2) at 550 degrees C in air, which is much lower than 1.56 Omega.cm(2) of pure YCF fiber cathode. Moreover, the distribution of relaxation times (DRT) analysis results indicate that the introduction of GDC nanoparticles and the core-shell structure greatly facilitate oxygen-ion conduction and charge transfer processes, and the oxygen incorporation process plays a major role in the total polarization resistance. The NiO-GDCIGDCIfibrous YCF-GDC fuel cell shows a maximum power density of 426.5 mW.cm(-1) at 550 degrees C. These results display that the core-shell fiber-structured YCF- GDC composite oxide is a promising candidate of highly active cathode for IT-SOFCs.