For the first time, the influence of fine variation of pH value of the chemical bath (6.5, 7.0 and 7.5) on structure, morphology, optical and photoresponse of SnS films was investigated. X-ray analysis revealed that the structure undergoes orthorhombic-to-cubic phase transformation at pH 7.0. Furthermore, a significant reduction in dark current value of photodetector, from µA to nA, occurred following this phase transformation. Under illumination of near infrared 750 nm, the photoresponse exhibited by the photodetector based on cubic structure was found to be faster 8 times compared to that based on orthorhombic structure, while the photosensitivity was 2.7 times higher. The estimated band gap energy of films lies between 1.51 and 1.73 eV with increasing pH value. The obtained results demonstrated the crucial role of fine pH value on the characteristics of nanostructured SnS films. © 2017 Elsevier B.V.