NiO film grown on Si(100) through RF magnetron sputtering at RT and at 100 °C shows (200) orientation, however, the structural quality of NiO is deteriorated by increasing the substrate temperature above100 °C.The deterioration of structural quality of the NiO film at higher substrate temperature is attributed to the decomposition of NiO film.The surface morphology shows a change in the granular structure above 100 °C. The Ni atomic percentage in the film increases by increasing the substrate temperature. The optical characterization revealed a small decrease in energy band gap by increasing the substrate temperature.