Copper monoxide is a popular p-type material in semiconductor and sensor technology. In this paper, Al-doped CuO thin film has been deposited on a glass substrate by the thermionic vacuum arc technique. The microstructural, morphological and optical properties were investigated. According to the X-ray diffraction patterns, the polycrystalline CuO material was obtained by means of the Al doping element. Using the Scherrer formula, the calculated crystallite size values are between 11 and 28 nm in different reflection planes. The thickness of the film was 50 nm. In the optical analysis, the average transmittance, absorbance and refractive index were 74%, 0.13, and 2.05, respectively. The optical band gap was 2.13 eV, which is in good agreement with the photoluminescence result. In the doping by Al, the band gap of the CuO shifted towards the visible region. Finally, the thin film is seen as a promising material for solar cell application.