The present invention relates to an electrolyte composition and method of making thereof. The proton conducting electrolyte composition i.e. Sr1-xBaxCe0.5Zr0.35Y0.1Sm0.05O3-δ, comprises combination of doped BaCeO3 and BaZrO3 by their doping in Sr, Y, and Sm, wherein x=0 to 0.99, and δ=0 to 0.1. The proton conducting electrolyte is used as at least one component, among others, of Solid Oxide Fuel Cells such Solid Oxide Fuel Cell (SOFC) can easily be operated at intermediate temperature about 600° C. thereby making the SOFC cost effective and reliable and showing highest power density.