In this article, we investigated the doping characteristics of Al-doped CuO (ACO), and Al/In co-doped CuO (AICO) thin films, which were synthesized on glass substrates, via the solution-based successive ionic layer adsorption and reaction (SILAR) technique. The surface morphological, chemical composition, structural, optical, and electrical properties of the nanocrystalline films were characterized by Field Emission Scanning Electron Microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier-transform Infrared Spectroscopy (FTIR), Ultraviolet–visible (UV–vis.) spectrophotometry, and Transmission Line Method (TLM), respectively. Surface morphology studies exhibited that a decrease in the films' thickness caused an increment in the optical transmittance. XRD patterns displayed that the obtained samples were polycrystalline and crystallized in a bare CuO monoclinic structure. FTIR studies of the CuO samples displayed that Al and In co-doping influenced the forms and the violence of the absorption bands. The optical bandgap energy of bare CuO was determined to increase from 1.45 to 1.78 eV as a result of the co-doping. The substitution of In displayed in the irregularity of the morphology, owing to its wide ionic radius, which caused an increase in band gap energy and a decrease in resistance. The co-doping of Al and In is hence anticipated to ensure an extensive range of physical and optical properties of nanostructured metal oxide samples for a variety of technological applications.