We present a novel approach to fabricate nitrogen-enriched porous carbon nanofiber networks based on electrospinning from a poly(acrylonitrile) (PAN) solution containing allyl polyethylene glycol (APEG), followed by a thermal treatment. During the pre-oxidation process, the APEG can react with the diene systems formed by the PAN elimination reaction via a Diels-Alder addition. The grafted APEG acts as a porogen, increasing the number and enlarging the size of the micropores, and also increases the nitrogen-doping level in the carbon nanofibers. When used as a binder-free electrode for supercapacitors, the nitrogen-enriched porous carbon nanofiber films can exhibit a specific capacitance of up to 302 F g(-1) at 0.2 Ag-1, retaining 94.6% of their capacitance after 2000 cycles. A power density of 10kWkg(-1) with an energy density of 5.2 Whkg(-1) can be achieved in an aqueous solution. The excellent electrochemical performance of the nanofiber films is attributed to their high specific surface area (753 m(2)g(-1)) and high nitrogen content (5.44%). (C) 2015 Elsevier Ltd. All rights reserved.