Synthesis and characterization of hot-pressed ion conducting nano-composite polymer electrolytes or polymer–matrix composites (NCPEs/PMCs):(1− x)[80PEO:20KI]: x SiO2 where 0< x <14wt.%, are reported. NCPEs were cast using a recently developed hot-press method in place of traditional solution-cast/sol–gel technique. Two and half orders of conductivity enhancement were found in NCPEs after the dispersion of nano-sized SiO2 inert material in the polymeric host, from the room temperature conductivity measurement. The polymer–salt/nano-filler SiO2 complexation, surface analysis and thermal properties characterization were done with the help of XRD, SEM, DSC and TGA studies. The ionic conductivity (σ) enhancements were explained using various experimental results viz. ionic mobility (μ), mobile ion concentration (n) values and various theoretical models. The ionic transference number (t ion) of optimum conducting composition of NCPE was also determined with the help of Transient Ionic Current (TIC) technique. To compute the activation energy (E a) in NCPEs, the temperature dependent conductivity studies were done and E a values were determined by using log σ–1/T Arrhenius plots. A solid state polymer battery was fabricated using the NCPE OCC as an electrolyte and cell-potential discharge characteristic studies were also reported with different load conditions at room temperature.