Carbone nanofibers prepared by electrospinning and subsequent steam activation were oxidized by treatment in HNO3 and HNO3/H2SO4 mixture. Surface morphology and degree of graphitic structure of oxidized nanofibers are affected mildly by acid oxidation according to SEM and Raman measurement. Nitrogen adsorption/desorption isotherms demonstrate decrease in specific surface area and pore volume of carbon nanofibers after oxidation. XPS spectra exhibit that oxidized nanofibers possess higher surface oxygen content than pristine nanofibers. Higher water adsorption capacities on oxidized nanofibers determined by water adsorption isotherms suggest the improvement of surface polarity and hydrophilicity. Furthermore, adsorption isotherms of benzene, butanone and ethanol show that surface oxidation enhances the adsorption tendency for butanone and ethanol on nanofibers due to increased surface polarity, indicating that the adsorption selectivity to polar organic compounds is improved. (C) 2013 Elsevier B.V. All rights reserved.