The recently reported sensing characteristics of the mixed-potential-type yttria-stabilized zirconia (YSZ)-based hydrocarbon (HC) sensor attached with ZnCr 2 O 4 -sensing electrode (SE) were found to be changed after the 10-day operation at 550°C under the wet condition (5vol.% water vapor). To improve the stability of the present sensor, the several modifications of the SE material by adding YSZ powder were examined. As a result, the sensor using the laminated (ZnCr 2 O 4 /YSZ)-SE gave the stable electromotive force (emf) response against 100ppm C 3 H 6 at 550°C for about one month examined. Based on the scanning electron microscopy (SEM) observation and the AC complex-impedance measurements, it was concluded that the stable behavior of the sensor using the laminated (ZnCr 2 O 4 /YSZ)-SE was provided by the stabilization of the interface between ZnCr 2 O 4 grains and YSZ particles. The fabricated sensor exhibited the linear dependence of sensitivity on the logarithm of either C 3 H 6 concentration (in the range of 20–800ppm) or mixtures of various hydrocarbons (HCs) (in the range of 90–2600ppmC). In addition, the emf response was not altered by the change of O 2 (2–20vol.%), H 2 O (0–10.8vol.%) and CO 2 (0–20vol.%) concentrations, and no interference of other gases (CO, NO, NO 2 , H 2 , and CH 4 ) was observed.