Three-dimensional (3D) core-shell silver nanowire (Ag NW) -polypyrrole (PPy) nanocomposites are used for the fabrication of supercapacitors. In-situ chemical polymerization of PPy onto Ag NWs results in the formation of diameter tunable, coaxial and 3D nanocomposites. Inner Ag NW core facilitates the charge transfer and PPy shell shows a remarkably high pseudocapacitance. Fabricated Ag NW/PPy nanocomposite has a specific capacitance of 509 F g(-1) at a current density of 0.31 A g(-1), while the energy and power densities are found to be 4.27 Wh kg(-1), 60.7 W kg(-1), respectively. For these devices a capacity retention of more than 90% is obtained following 10000 cycles. It is envisaged that the 3D core-shell nanocomposite architecture investigated here can be extended to other conducting polymer and metal nanowire systems.