Zinc oxide (ZnO) thin films were deposited on silicon substrates by reactive RF magnetron sputtering technique in order to investigate the evolution of the morphological and the optical properties as a function of different RF power and substrate temperature. Analysis of RF power and the substrate temperature have played a significant role in the morphological and the optical properties of the sputtered ZnO thin films. X-ray diffraction pattern of ZnO thin film has shown the appearance of c-axis-oriented (002) peak for all samples with variation in the degrees of crystallinity. The surface roughness as well as the average grain size of the ZnO films found to be decreased with RF power, where as the films grown at higher temperature has shown the evolution of larger grains. ZnO films, deposited at 150 W RF power and substrate of 200°C, have shown better optical properties.