We attempted to fabricate new electrochemical cells for NOx decomposition using high-oxygen-ion-conducting materials with a multilayer cathode operable in the intermediate temperature. The NO decomposition measurements as a function of temperature of the cells were carried out to clarify the correlation between the oxygen ion conductivity of the solid electrolyte and the NOx decomposition properties. The NO decomposition by the electrochemical cell with a NiO-ScCeSZ catalytic layer started at around 325 degrees C and it was shown that the starting temperature and the efficiency of the NOx decomposition is attributed to the oxygen ion conductivity of the electrolyte. (c) 2006 The Electrochemical Society.