inorganic non-toxic metal halide perovskites have taken the dominant place in commercialization of the optoelectronic devices. The first principles simulation has been executed with the help of density functional theory to investigate the structural, optical, electronic and mechanical properties of nontoxic csSncl 3 metal halide under various hydrostatic pressures up to 40 GPa. The analysis of optical functions displays that the absorption edge of CsSnCl 3 perovskite is shifted remarkably toward the low energy region (red shift) with enhanced pressure. The absorptivity, conductivity and the value of dielectric constant also increases with the applied pressure. the investigation of mechanical properties reveals csSncl 3 perovskite is mechanically stable as well as highly ductile and the ductility is increased with increasing pressure. the investigation of electronic properties shows semiconducting to metallic transition occurs in csSncl 3 under elevated pressure. The Physics behind all these changes under hydrostatic pressure has been analyzed and explained in details within the available Scientific theory. In recent years, metal halide perovskite materials of the renowned formula AMX 3 (where, A = a cation, M = a metal ion, and X = a halogen anion) have attracted immense attention of the researchers due to their noticeable solar cell potency with extraordinary optoelectronic characteristics including wide range of absorption spectrum, enhanced optical absorption, tunable band gap, extended charge diffusion, high charge carrier mobility and low carrier effective masses 1,2. The researchers established the application of these semiconducting materials are also wide in the field of electronic devices such as LEDs (Light Emitting Diodes), photodetector, and the devices which are extensively used for solar to fuel energy conversion 3-6. Moreover, these metal halide perovskites are cheap and available in a large quantities on the earth. Consequently, these halide perovskite semiconductors would be more suitable and beneficial in solar cells application compared to the Si-based photovoltaic (PV) technology 1. However, most of the perovskite halides with excellent properties comprise of lead (Pb) which is harmful for the environment 7-9. Due to the environment contamination and worldwide energy crisis, clean and sustainable energy sources have taken great attention. Therefore, a large number of experimental and theoretical works have been performed by replacing Pb with a suitable metal cation in the last few years 10-13. The study of mechanical properties reported by Roknuzzaman et al. 10 demonstrates that the non-toxic CsSnCl 3 perovskite has ductility entity but the halide perovskite semiconductor shows large band gap value (2.8 eV) 11. As a result, the CsSnCl 3 shows medium optical absorption and not appropriate for remarkable efficiency solar cells application. For this purpose, we have reported metal-doped CsSnCl 3 to find a better Pb-free perovskite semiconductor for high potency solar cell application in previous ...