Mixed-potential type YSZ-based sensor utilizing In₂0₃as sensing electrode (SE) was fabricated and examined for detection of NO₂at 700℃. The hierarchical In₂0₃oxide material was synthesized via a facile hydrothermal process, and In₂0₃sintered at different temperatures were characterized using Xray diffraction (XRD) and field-emission scanning electron microscopy (FESEIV1). The present study mainly focused on the effect of sintering temperature of SE materials (800℃, 1000℃, 1200℃) on NO₂sensing characteristics. As a result, the sensor attached with In₂O₃-SE calcined at 1000℃exhibited the largest sensitivity to NO₂, which the response to 100 ppm NO₂was as large asl 26 mV and excellent long-term stability for 30 days tested at 700℃. It is noteworthy that the NO₂sensitivities for present device showed a small influence by the change of relative humidity at 700℃. Additionally, the present devices also displayed good repeatability, the excellent sensitivity and relatively good selectivity in conjunction with various interfering gases before and after 30 days high-temperature-aging of 700℃. It was speculated that the largest sensing performance for the sensor attached with In₂0₃-SE sintered at 1000℃was contributed to the special micro-structure of the SE and the highest electrochemical catalytic activity for cathodic reaction of NO₂at the triple phase boundary (TPB).