Temperature dependence and selectivity of potentiometric NO2 sensors (MOx/YSZ/Pt, where MOx = Cr2O3, SnO2, and CeO2) were studied in 21% O-2. All the sensors showed the same direction of NO2 response with each other and a linear relationship in the plot of the electromotive force vs the logarithm of NO2 concentration. NO2 selectivity behavior of the sensors was similar, such that the selective NO2 detection was achieved against CO and CO2, but the addition of O-2, NO, and H2O made a significant change in the NO2 response. This similarity in response is likely due to similarity in the catalytic activity of the MOx electrode elements. (c) 2006 The Electrochemical Society.