Co-doped PbS thin films with different Co concentrations were synthesized by cost-effective chemical bath deposition technique. The main purpose of this study is to determine thin film which has the best photovoltaic efficiency by examining the photovoltaic properties of Co-doped PbS with different Co concentrations. To investigate photovoltaic properties, incident photon-to-current efficiency (IPCE) and current density (J)-voltage (V) measurements were performed. The second stage of our study is to characterize the properties of Co-doped PbS which has the best photovoltaic efficiency value. As a result of the characterization processes, the information about the crystal structure, crystallite size and energy band gap of Co-doped PbS was obtained. When the photovoltaic efficiency values obtained in the first stage of our study were taken into consideration, it was clearly observed that the Co-doped metal significantly improved the photovoltaic properties of the PbS.