Trace nickel oxide-embedded hierarchical porous carbon nanofibers (CNF-NiO) were fabricated by electrospinning polyacrylonitrile-Ni(NO3)(2) (PAN-Ni) followed by stabilization, carbonization and acid treatment. The resultant CNF-NiO was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, thermo gravimetric analysis and nitrogen adsorption-desorption isotherm. The NiO amount and porous structure can be tuned by varying the PAN/Ni ratio and acid treatment time. The electrochemical properties of the electrospun CNF-NiO nano fibers were analyzed by cyclic voltammetry and impedance method. The specific capacity of 157.9 Fig was obtained at the PAN/Ni mass ratio of 90:3 with 3 h HCl wash. This porous CNF-NiO composite has been applied as a self-supporting cathode for capacitive deionization. The desalination amount arrived at 6.2 mg/g, which is 3 times as high as that of the electrospun pure carbon fibers. Longer wash time leads to decreased capacitance and desalination performance. (C) 2018 Elsevier Inc. All rights reserved.