Perovskite oxides are promising multi-functional materials with enhanced physical and chemical properties. In this study, high-crystalline SrMnO3 perovskite oxide nanofibers have been successfully synthesized by sol-gel electrospinning followed by calcination at different temperatures, using polyvinylpyrrolidone as a sacrificial polymeric binder. The change in porosity and grain size with calcination temperature imparted a substantial effect on the electrochemical properties of the obtained SrMnO3 nanofibers. The SrMnO3 nanofiber electrode calcined at 700 degrees C exhibits an electrochemical capacitance of 321.7 F g(-1) at a discharge current density of 0.5 A g(-1). The effect of doping Ba/Ca on Sr, and Co/Fe/Ni on Mn, respectively, on the specific capacitance of SrMnO3 nanofibers is studied. 20 mol% Ba loading shows the best performance as a supercapacitor electrode with a specific capacitance of 446.8 F g(-1) at a discharge current density of 0.5 A g(-1). The nanofibers retained 87% its initial capacitance after 5000 successive cycles. The device fabricated using the nanofibers show an energy density of 37.3 W h kg(-1) at a power density of 400 W kg(-1), and it is retained as 15.7 W h kg(-1) even at a high-power density of 8006 W kg(-1), indicating the potential of this electrode material for high-rate charge/discharge operations in supercapacitors.