Thin films of magnesium nickel sulphide (MgNiS) were grown on glass substrates using the chemical bath deposition (CBD) techniques at room temperature. Effects of deposition time on the optical and structural properties of the films were studied via depositing MgNiS thin films for different dip time. The optical properties of the deposited films were investigated by measuring the optical absorbance of the films at the normal incident of light in a range of 200–1000 nm with a Janway 6405 UV–VIS spectrophotometer. From the absorbance values, other properties such as transmittance, reflectance, thickness, and energy gap, were calculated. The low reflectance and large band gap make the film good materials for antireflection coatings and absorber layers of solar cells, respectively. The films grown were further characterized using an MD10 version 2.0 X–ray diffractometer and an Olumpus optical microscope to determine the structural properties of the films. From the XRD results, the film crystal structure was found to be rhombohedral. The lattice constant and an average grain size of the grown films were found to be 5.32 Ǻ and 0.45 μm, respectively. The presence of large peak indicates that the MgNiS film is polycrystalline.