Nickel oxide (Ni1-xO) films deposited by RF reactive magnetron sputtering were investigated at various substrate temperatures ranging from room temperature to 250 degrees C for uncooled infrared image sensor applications. The structural properties measured by X-ray diffraction and X-ray photoelectron spectroscopy showed that the deposited films had a Ni-deficient structure and that films deposited at a higher temperature showed more crystallized structures with fewer microstructural defects. These defects had an effect on several properties influencing the sensing performance. The conductivity was found to decrease from 9.47 to 0.10 S/cm with the deposition temperature. In addition, with an increase in the deposition temperature, both the absolute temperature coefficient of resistance and the normalized Hooge parameter, representing the magnitude of 1/f noise, increased from 1.56%/K to 2.76%/K and from 9.12x10(-28) to 2.40x10(-27) m(3), respectively. (alpha H/n)(1/2)/vertical bar beta vertical bar, a useful figure of merit determining the performance of infrared sensor, was varied in the range of 1.77x10(-14) and 2.06x10(-14) m(3/2)K/% with the deposition temperature, and the best performance was obtained from the film deposited at 250 degrees C. Consequently, the nickel oxide film is deemed to be a good potential candidate for uncooled infrared sensor applications.