GDC (gadolinium-doped ceria) is well known as a high oxygen ionic conductor and is a catalyst for the electrochemical reaction with methane fuel leading to the oxidation of deposited carbon that can clog the pores of the anode and break the microstructure of the anode. NiO/GDC-GDC dual nano-composite powders were synthesized by the Pechini process, which were used as an AFL (anode functional layer) or anode substrates along with a GDC electrolyte and LSCF-GDC cathode. The anodes, AFL, and electrolyte were fabricated by a tape-casting/lamination/co-firing. NiO-GDC anode and NiO/GDC-GDC anode-supported unit cells were evaluated in terms of their power density and durability. As a result, the NiO/GDC-GDC dual nano-composite demonstrated an improved power density from 0.4 W/cm(2) to 0.56 W/cm(2) with H-2 fuel/air and from 0.3 W/cm(2) to 0.56 W/cm(2) with CH4 fuel/air at 650 degrees C. In addition, it could be operated for over 500 h without any degradation with CH4 fuel. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.