Core-shell nanoparticles of Au@Ni bimetal with the composition of Au:Ni = 85:15 was developed successfully by facile co-reduction and annealing synthesis route. The forming mechanism of the nano core-shell was proposed. The annealing conditions based on the morphology, microstructure and evolution of the core-shell structures were analyzed and revealed by scanning electron microscope in detail. The core-shell structures were well kept after the uniform films of Au85Ni15 were annealed on top of the GDC (Ce0.9Gd0.1O1.95) electrolyte. The complex impedance of the symmetrical half cells of Au@Ni/GDC/Au@Ni was performed at 500 degrees C. Under the optimal annealing conditions, the area specific resistance for the cathode on top of GDC was 0.25 Omega cm(2) at 500 degrees C. And the power density of the anode supported cell Au@Ni/GDC/-NiO with the optimal profile was 153, 292, 464, 590, and 835 m Wcm(-2) at 450, 475, 500, 525, 550 degrees C, respectively. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.