Mixed potential phenomena occurring at the oxide/YSZ electrode in the presence of NO2-containing air is explained in terms of the absolute potential model, which demonstrates how maintaining a non-equilibrium state with gas phase. through catalytic inactiveness of the electrode, is important to obtain a noticeable EMF response to NO2 and NO. The direction, of the EMF response of oxide electrodes to NO and NO2 gas are coincident with the prediction from the absolute potential analysis. Simulated results of anodic and cathodic Currents for Pt electrode clearly show the insensitivity to NO2 and NO as suggested in the analysis. (c) 2005 Elsevier B.V. All rights reserved.