Abstract: CuS thin films of average thickness between 0.498 and 0.548 μm were grown on glass substrates at 300 K by chemical bath deposition technique and annealed at various temperatures. The optical constants (index of refraction n, extinction coefficient k and absorption coefficient α) were determined using the absorbance and transmission measurement from a Unico UV-2102 PC spectrophotometer, at normal incidence of light in the wavelength range of 200-1000 nm. The films have high absorption of greater than 90% in the UV region but with moderate transmission of which is greater than 30% but less than 65% throughout the entire VIS-NIR spectrum. The average refractive index (n) is between 2.07 and 2.26 while the average extinction coefficient is between 0.049 and 0.063. The refractive index greater than 2.0 makes the material a good candidate for protective coatings. The plot of (ahv)2 against (hv) showed that the material has a direct band gap between 1.60 eV and 2.40 eV while the plot of (ahv)½ against (hv) has an indirect band gap between 1.20 eV and 1.60 eV. The band gap study show a transition of from a direct Cu2S to an indirect CuS thin film. The high absorbance of the films made them good materials for large area selective coatings for photothermal conversion of solar energy.