Four types of anodes have been prepared on Ce0.9Gd0.1O1.95 (GDC) electrolyte pellets with two kinds of NiO and GDC powders to investigate the effect of microstructure on electrochemical performance of Ni-GDC composite anodes. The anode/electrolyte interfacial polarization resistances are characterized using impedance spectroscopy under open circuit conditions. The results show that the cell performance depends strongly on the anode microstructure, which in turn is determined by the anode compositions and fabrication conditions. By carefully adjusting the anode microstructure, the GDC electrolyte/anode interfacial polarization resistances have been dramatically reduced. For example, the interfacial resistance at 600degreesC was decreased from 1.61 Omega cm(2) for the anodes prepared using commercially available powders to 0.06 Omega cm(2) for those prepared using powders derived from a glycine-nitrate process. (C) 2004 Elsevier B.V. All rights reserved.