A solid oxide fuel cell (SOFC) unit is constructed with Ni-(Ce,Gd)O2-x as the anode, yttria-stabilized zirconia as the supporting electrolyte, and Cu-added (LaSr)(CoFe)O-3-(Ce,Gd)O2-x as the cathode. Both reduction and oxidation of NO occur and are affected by the concentration of NO. Either reduction or oxidation of NO starts from NO adsorption. NO reduction to generate an electrical current has very much smaller activation energy than NO oxidation to form NO2. With 4% O-2 and 1000 ppm NO, the NO2 yield is relatively small and the temperature effect on NO reduction is positive. These are beneficial for the application of the process of DeNO(x) by SOFC to NO abatement from the lean-burn engine exhausts. (C) 2010 Elsevier B.V. All rights reserved.