Simultaneous detection of NO concentration and temperature by a single sensor element was investigated. Resistance of the mixed oxide of 20SrSnO(3)-80Fe(2)O(3) was independent of gas, but decreased linearly with increasing temperature. However, capacitance of 20SrSnO(3)-80Fe(2)O(3) decreased with increasing NO concentration, although it was hardly changed upon exposure to CO and CH4 and not significantly changed by CO2 and H2O. Therefore, NO concentration and operating temperature of sensors can be estimated simultaneously by monitoring the capacitance and the resistance of the 20SrSnO(3)-80Fe(2)O(3) mixed oxide. It is expected that the sensitive detection of NO can be achieved by the simultaneous detection of NO and temperature using 20SrSnO(3)-80Fe(2)O(3), since capacitance was strongly affected by temperature.