Optimization studies towards the formation of single phase orthorhombic SnS and Sn2S3 thin films are independently achieved using SnS target in RF magnetron sputtering by varying the RF power, in-situ and post deposition vacuum annealing temperature. Micro structural analyses confirmed the role of in-situ annealing at 400 degrees C for the columnar growth formation of single phase SnS nanostructures which is an important aspect towards the fabrication of SnS based thin film solar cells with improved efficiency. Further, SnS to Sn2S3 phase transition is observed at 500 degrees C. The observed variations in the optical properties such as band edge shift, direct energy band gap (Eg), absorption coefficient (alpha), extinction coefficient (K) and refractive index (n) of the films are correlated with the structural and morphological analysis. Electrical studies along with band gap measurement further confirmed the transition from p-type SnS phase having a band gap value of 1.55 eV with resistivity as 1280 Omega cm to n-type Sn2S3 with band gap value of 1.06 eV and resistivity of 0.864 Omega cm.