Sulphur doped Co3O4 (S-Co3O4) nanostructured thin film has been produced by ultrasonic spray pyrolysis (USP) method. The film has been characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDAX), Fourier transform infrared (FT-IR) and Raman spectroscopy. The surface appearance of the film was obtained using scanning electron microscope (SEM). Optical reflectance and transmittance spectra were recorded with a double beam spectrophotometer equipped with an integrating sphere. The optical constants such as refractive index, extinction coefficient, optical conductivity, real and imaginary parts of the dielectric constant of the film were calculated. The XRD pattern shows that the film has only clear diffraction peaks around 2θ = 29.26o corresponding to the (111) plane of cubic Co3O4. The crystallite size was calculated to be approximately 24 nm. The Raman measurements revealed four peaks of Co3O4. Infrared spectrum of the film has been investigated in 500–3000 cm−1 region.