A solid oxide fuel cell unit is constructed with Ni-YSZ as the anode. YSZ as the electrolyte, and Cu-added La0.8Sr0.2MnO3-Ce0.9Gd0.1O1.95 as the cathode. Cu addition is done by impregnation and doping, respectively. It is found that zero NOx emissions can be achieved no matter how large the inlet NO concentration is in the simulated diesel exhaust. The major driving force for NOx conversion is not the electrical power. Cu addition by impregnation results in larger rate of NO decomposition than that by doping. At 600 degrees C. both NO and NOx conversions increase with increasing O-2 concentration from 6 to 14%. Lower temperature is beneficial for the NOx conversion. Both very low and very high NO concentrations are beneficial for the NO and NOx conversions. (C) 2011 Elsevier B.V. All rights reserved.