Solid polymer electrolytes (SPEs) made up of PVDF-HFP poly (vinylidene fluoride hexafluoropropylene) with different concentrations of Mg (ClO4)2 (Magnesium perchlorate) are produced using a solution cast technique. UV, DSC, and electrical impedance spectra are used to investigate optical, thermal, and electrical characteristics. Optical absorbance, direct and indirect band gaps of SPEs are revealed by studies of UV-visible spectra and found to decrease both band gap values with Mg salt concentration to PVDF-HFP polymer. The structural changes in the sample due to endothermic and exothermic heat flow are studied by DSC. Electrical impedance spectra disclosed the bulk resistance and ionic conductivity. Among all the samples of PVDF-HFP: Mg (ClO4)2 SPEs of 400mg of Mg (ClO4)2 included PVDF-HFP polymer electrolyte exhibits lower direct and indirect band gap, low bulk resistance, and good electrical conductivity (σ = 5.70 × 10-4 Scm-1).