Bismuth sulphide (Bi2S3) thin films are deposited on microscope glass slides by single source thermal evaporation technique. The properties of the films are analysed by X-ray diffraction, Raman spectroscopy, atomic force microscopy and UV-Vis. spectrophotometry. The effect of post deposition vacuum annealing and thickness on the properties of the films are investigated. The X-ray diffractograms revealed the polycrystalline nature of annealed films which exhibited orthorhombic crystal structure. The films exhibited characteristic Raman peaks at 238 and 260 cm-1. The as-deposited films are found to have nano-sized particles through AFM measurements. The calculated direct optical band gap of the films thickness is in the range of 2.5-1.7 eV.