Polyaniline is grafted onto the surface of high conductivity carbon nanotube-embedded carbon nanofibers (PANi-P-1.0) via plasma modification to fabricate an electrode for a high performance supercapacitor. The structure and morphology of polyaniline graft onto the carbon nanofiber (CNF) are confirmed by Raman, X-ray photoelectron spectroscopy, electron microscopy and transmission electron microscopy. The emeraldine base form of nanorod-polyaniline is well-distributed on the surface of the CNF. The PANi-P-1.0 has a high specific capacitance of 606 Fg(-1). From the result of the electrochemical properties, the high capacitance is contributed by the electric double layer capacitance of the high conductivity CNF and the pseudocapacitance of the grafting polyaniline. In addition, compared to polyaniline coated on the surface of the CNF, the electrochemical properties of the PANi-P-1.0 are improved by reducing the charge transfer resistance (Rct) from 13.54 to 3.87 Omega, theWarburg coefficient from 101.39 to 47.96 Omega s(-1/ 2) and the relaxation time constant from 0.794 to 0.194 s due to the covalent bond between the polyaniline and CNF. The PANi-P-1.0 also show excellent cycling stability after 1,000 cycles of galvanostatic charge and discharge because the free space around the grafting polyaniline allows volumetric change. (C) 2016 Elsevier Ltd. All rights reserved.