Synthesis, characterization and polymeric battery studies of Na + ion conducting NanoComposite Polymer Electrolyte (NCPE) membranes: (1-x) [75PEO: 25NaPO 3 ]: x SiO 2 , where x = 0 -15 wt. (%), has been reported. NCPE membranes have been casted using a novel hot-press technique in place of the traditional solution cast method. The dispersal of SiO 2 in SPE host: (75PEO: 25NaPO 3 ), a conductivity enhancement of an order of magnitude achieved in NCPE film: [93 (75PEO: 25NaPO 3 ): 7 SiO 2 ]. This has been referred to as Optimum Conducting Composition (OCC). Material characterizations have been done with the help of XRD, SEM and DSC techniques. The ion transport behaviour in hot-pressed NCPEs has been discussed on the basis of experimental measurements on some basic ionic parameters viz. conductivity (σ), ionic mobility (µ), mobile ion concentration (n) and ionic transference number (t ion ). The temperature dependent conductivity studies have been done to compute the activation energy (E a ) values from the 'log σ -1/T' Arrhenius plots. The ion conducting solid state polymeric battery was fabricated and cell-potential discharge characteristics have been studied at different load conditions.