In this paper, we investigated the sensing properties of oxygen gas sensors in which the nanostructured TiO2 thin films buried with Pd layer serve as the semiconducting materials. The nanostructured titania thin films for O2 sensors were prepared with the sol-gel process by using the Ti butoxide-derived sol and were processed by heat-treatment at 500 °C. The TiO2 square board with an area of 350 μm × 350 μm was prepared by wet etching. On the square board, 150 nm Pt micro interdigitated electrodes with 50 nm Ti buffer layer were fabricated by lift-off process. X-ray diffraction(XRD) analysis of TiO2 film results indicated the crystal phase of TiO2 thin films was anatase, and SEM observation showed the average size of TiO2 thin films buried with Pd layer crystals were decreased compared with the pure TiO2 thin films. Electric resistance of the O2 sensor was monitored to evaluate its performance and the results showed that the sensor outputs stable signal with good response properties.