Porous NiO nanofibers (NFs) with an average diameter of 280-400 nm have been fabricated directly on nickel foam current collector (NiO-NFs/Ni) by a simple electrospinning technique followed by appropriate heat treatment. The as-obtained NiO-NFs/Ni is used as a binder-free electrode in supercapacitors and its electrochemical performance is evaluated by cyclic voltammetry, galvanostatic charge/discharge test and electrochemical impedance spectroscopy. The results reveal that the binder-free NiO-NFs/Ni electrode can offer reasonably high specific capacitance (737 Fg(-1) at 2 Ag-1), excellent rate capability with capacitance retention as high as 570 Fg(-1) even at 40 Ag-1, and very good cycling stability at various rates up to 8000 cycles. The excellent performance can be attributed to the porous nature of both the NiO-NFs and Ni foam current collector as well as the binder-free feature of the electrode, which greatly facilitate the ion and electron transport in the electrode. (C) 2015 Elsevier B.V. All rights reserved.