<p>Herein, a simple and cost-effective chemical bath deposition methodology was employed to synthesize Co-doped SnS thin films, focusing on the improvement of the optical and electrical properties of the films by modulating the Co²⁺ ion concentrations in the reaction solution. X-ray diffraction analysis revealed a phase transformation from amorphous to a Herzenbergite orthorhombic phase with increasing Co²⁺ concentration. Chemical structure analysis via X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy confirmed the incorporation of Co²⁺ ions, along with the presence of SnS, Sn₂S₃, and minor CoO phases. Optical studies demonstrated a significant bandgap widening from ~ 1.0&#xa0;eV (undoped) to ~ 1.7&#xa0;eV (Co-doped), making the films suitable for photovoltaic applications. Electrical characterization showed a marked decrease in resistivity from ~ 3 × 10⁹ to 22 × 10⁶ Ω&#xa0;cm. These results highlight the potential of Co-doped SnS thin films for next-generation photovoltaic devices, emphasizing the importance of doping optimization to balance performance and structural integrity.</p>