<p>In this study, the effects of silver (Ag) doping on the structural, morphological, optical, and electrical properties of tin monosulfide (SnS) thin films were investigated. The films, undoped and doped with 3%, 6%, and 9% Ag, were deposited using the ultrasonic spray pyrolysis (USP) technique at a substrate temperature of 350 °C. X-ray diffraction (XRD) analysis confirmed a <i>π</i>-SnS (cubic) structure with (400) preferred orientation for undoped and ≤ 6% Ag-doped films, while 9% doping induced amorphization due to severe lattice distortions. Morphological analyses revealed smooth, void-free surfaces, with average roughness increasing from 5.8 nm (undoped) to 19.6 nm (9% doping). Optical measurements showed that the band gap widened from 1.84 eV (undoped) to 2.47 eV (9% Ag-doped), and Urbach energy increased from 190 meV to 600 meV. Hall effect measurements confirmed p-type conductivity for all films. Resistivity ranged from 4.34 × 10⁵ Ωcm to 9.48 × 10⁵ Ωcm, carrier concentration varied between 2.7 × 10¹² cm^-3 and 5.6 × 10¹² cm^-3, while mobility decreased from 3.3 × 10¹ cm²/Vs to 2.0 × 10¹ cm²/Vs with increasing Ag doping. These findings demonstrate that Ag doping significantly influences the structural and optoelectronic behavior of SnS thin films, making them promising candidates for thin-film solar cells and optoelectronic applications.</p> Graphical Abstract <p></p>