Organic-inorganic hybrid nanocomposites have attracted attention in optoelectronic devices because they incorporate the preferable properties of organic and inorganic components within a single composite. This study investigated the influence of the choice of mixed-solvent system and reaction temperature on in situ, surfactant-free synthesis of P3HT:SnS nanocomposites. We observed that both these parameters significantly affect the structural and optical properties of the nanocomposite. We have explained this based on variation in Hansen Solubility parameters for the solvent:polymer system as a function of solvent composition and temperature. We calculated the relative energy distance (RED) values for the mixed-solvent systems viz; Dichlorobenzene-Dimethyl sulfoxide (DCB-DMSO) and Chlorobenzene- Methanol (CBZ-MT) systems, as a function of temperature. We observed that the morphology of inorganic structures and their distribution are strongly affected by the choice of the mixed solvent system and the reaction temperature. It is concluded that with proper selection of mixed-solvent system and reaction temperature, it is possible to achieve P3HT:SnS nanocomposites with well-distributed nanostructures in a polymer matrix without using any surfactant.