In this work, we developed a high-response mixed potential type yttria stabilized zirconia (YSZ) based planar gas sensing device utilizing CoTiO₃sensing electrode (SE) prepared via a facile sol-gel method to sensitively detect NO₂at an operating temperature of 650℃. The present gas sensor coupled with 1200℃-sintered CoTiO₃-SE exhibited high responses to NO₂in the concentration range of 500 ppb-200 ppm, as the value of the response was 130 mV to 100 ppm NO₂. A linear relationship was observed between the Delta V of the sensor and the logarithmic scale of the NO₂concentration, which the sensitivity was 60 mV/decade. In addition, the sensor also displayed good reproducibility, the maximum response change of 5.4% and 16% in different coexisting gases and 98% high relative humidity, and response decrease of 6.9%-100 ppm NO₂after high temperature test for 20 days. Moreover, the sensing mechanism of sensor, which was based on mixed potential model, was confirmed using polarization curve measurements in air and different concentrations of NO₂.