Nitrogen-doped porous carbon spheres (NPCSs) were prepared through a fast microwave-assisted approach using sucrose as the precursor in a microwave system and subsequent thermal treatment in ammonia atmosphere at different temperatures. The morphology, structure and electrochemical performance of the NPCSs were characterized by scanning electron microscopy, nitrogen adsorption-desorption, X-ray photoelectron spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy, and their electrosorption performance in NaCl solution was studied. The results show that NPCSs treated at 1000 degrees C exhibit an extremely high electrosorption capacity of 14.91 mg g(-1) when the initial NaCl concentration is 1000 mg l(-1), which shows great improvement compared with their undoped counterpart. The nitrogen doping is suggested to be a very effective method to improve the electrosorption performance, and the NPCSs should be a very promising candidate as electrode material for CDI application. (C) 2015 Elsevier Ltd. All rights reserved.