The series LaxSr1-xNiO3-delta (0.3 <= x <= 1) nanofibers (LNF-x) samples are prepared by using electrospun method. We investigate the structure and the electrochemical properties of LNF-x in detail. As a result, LNF-x nanofibers present a perovskite structure, and the LNF-0.7 sample with high specific surface area display remarkable performance as an electrode material for supercapacitors. The maximum specific capacitance value of 719 F.g(-1) at a current density of 2 A.g(-1), which retains 505 F.g(-1) at a high current density of 20 Ag-1, is obtained for LNF-0.7 electrode in 1 M Na2SO4 aqueous electrolyte. Moreover, the LNF-0.71/LNF-0.7 symmetric supercapacitor device using 1 M Na2SO4 aqueous solution is successfully demonstrated. The capacitor device can operate at a cell voltage as high as 2V, and it exhibits an energy density of 30.5 Wh.kg-1 at a high power density of 10 kW.kg(-1) and a high energy density of 81.4 Wh.kg(-1) at a low power density of 500 W"kg(-1). More importantly, this symmetric supercapacitor also shows an excellent cycling performance with 90% specific capacitance retention after 2000 charging and discharging cycles. Those results offer a suitable design of electrode materials for high-performance supercapacitors. (C) 2015 Elsevier Ltd. All rights reserved.