We have fabricated a mixed-potential-type yttria-stabilized zirconia (YSZ)-based sensor and examined its sensing characteristics to methane (CH4) at high operating temperatures. Among various oxide sensing electrodes (SEs) tested, In2O3 was found to give the highest sensitivity as well as good selectivity to CH4 at 790 degrees C, although the response was very slow. To improve the response rate, sintering temperature of In2O3-SE was changed in the range of 1200-1400 degrees C. As a result, the sensor attached with the 1300 degrees C-sintered In2O3-SE showed quicker response which was about fifteen times higher than that for the 1400 degrees C-sintered In2O3-SE.