The relationship between the electrochemical performance of an anode in a solid oxide fuel cell and the distribution of yttrium-doped barium zirconate (BZY) in the electrochemically active zone of nickel (Ni)/yttria-stabilized zirconia (YSZ) anodes was investigated to clarify the promoting effect of BZY on electrochemical reaction. After BZY was injected into Ni/YSZ anodes using an ink-jet technique for control of the distribution of BZY, the anode performance improved in both humidified H-2 and dry CH4 fuels. The performance of the BZY-infiltrated Ni/YSZ anodes depended on the distribution of BZY; an increasing gradient of BZY from the electrolyte side to the anode surface side was particularly effective in improving the performance. These results suggest that the optimum amount of infiltrated BZY to enhance the electrochemical reaction depended on the distribution of the oxygen chemical potential in the Ni/YSZ anodes. According to the competitive adsorption equilibrium of reactants and the Langmuir-type reaction on the surface of Ni at the triple-phase boundary, the oxygen coverage was a critical factor in the electrochemical reaction and depended on the oxygen chemical potential. In conclusion, the enhanced electrochemical reaction in the BZY-infiltrated Ni/YSZ anodes was therefore due to the increased oxygen coverage. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.068207jes] All rights reserved.