Solid oxide fuel cells (SOFCs) are considered as important green energy devices for the 21^st century due to its high chemical to electrical energy conversion efficiency, modular design and fuel flexibility. However, the widespread commercialization of SOFCs has not been realized due to its cost associated with cell fabrication, electrode/ electrolyte materials and its maintenance. The conventional electrolyte, Yttria-stabilized Zirconia requires high operating temperature (800 - 1000 ⁰C) to achieve sufficient oxide-ion conductivity, which increases the cost and exacerbates the instability between the components [1]. Therefore, there is considerable interest in developing alternative electrolytes with oxide ion conductivity > 10⁻² S/ cm at intermediate temperature (IT) (500 - 700 ⁰C). Hence, here we successfully synthesized IT electrolytes Sr_1−xNa_xSiO_3−d (x = 0.0, 0.45) by solid state reactions. XRD, Solid state NMR, FE-SEM/ EDS and impedance spectroscopy are used for the structural and electrical studies. From the XRD, it is evident that both the samples can be indexed in monoclinic c2/c space group (15) [2]. ²⁹Si solid state NMR reveals a sharp single peak at −86 ppm for SrSiO₃. Broadening of the peak at ~ −89 ppm indicates the presence of glassy Na₂Si₂O₅ phase in Sr_0.55Na_0.45SiO_3−d [3]. FE-SEM image of Sr_0.55Na_0.45SiO_3−d clearly shows the amorphous Na₂Si₂O₅ dispersed in SrSiO₃ insulating crystalline phase. EDS analysis confirms that grain is Na-deficient (SrSiO₃) and grain boundary (GB) is Na-rich phase (Na₂Si₂O₅). The doping of Na into SrSiO₃ leads to the formation and segregation of glassy Na₂Si₂O₅ along the GBs, which is the main reason for high electrical conductivity. Among, Sr_1−xNa_xSiO_3−d (x = 0.0, 0.45), SrSiO₃ behaves as an insulator and Sr_0.55Na_0.45SiO_3−d exhibits highest conductivity in the measured temperature range, which makes it as electrolyte for intermediate temperature SOFCs.