Heteroatom doping endows magnetic carbons with unique electronic features and rich surface chemistry, significantly enhancing their adsorption performances for the environmental remediation. In this work, fluorine and nitrogen co-doped magnetic nanocarbon fibers (FN-MCFs) were prepared via a facile carbonization method combined with electrospinning procedure. FN-MCFs were used as adsorbents for Cr (VI) removal, displaying a remarkable activity with as high as 153.61 mg/g and 0.58 mg/m(2) of the Cr (VI) removal ability. F and N co-doping in magnetic nanocarbon fibers offered a higher specific surface area and disorder degree in graphite layer, therefore providing more active sites on the adsorbents surface. The electrostatic adsorption and reduction reaction between the Fe-0, Fe2+ nanoparticles or edge carbons and Cr(VI) ions played significant roles in the adsorption process, which was believed to be facilitated by F and N co-doping. It was found that chemical adsorption was the main process in this work. Moreover, the adsorption capacity of FN-MCFs was majorly influenced by the doping level or doping type. F doping was found to be more important than N doping for the Cr(VI) removal in the dual doping system. In addition, the excellent reusability of the FN-MCFs was observed. (C) 2018 Elsevier Inc. All rights reserved.