Polyacrylonitrile (PAN) nanofibers (prepared by an electrospinning technique) were chemically modified with hydrazine. The Fourier transform infrared spectrum of the hydrazine-modified polyacrylonitrile (HM-PAN) showed that the intensity of the nitrile peak (2250 cm(-1)) of the PAN nanofibers decreased significantly after treatment with hydrazine. New peaks at about 3400-3100 cm(-1) (NAH stretching vibration) also appeared, which showed that the hydrazine was chemically attached to the PAN nanofibers. HM-PAN had a smooth surface (as confirmed by a scanning electron microscopy) and was a suitable material for the adsorption of metal ions from aqueous solutions. The adsorption capacity of HM-PAN increased as the adsorption time increased and became constant at 114 and 217 mg/g for Cu(II) and Pb(II) ions, respectively, after 24 h. In addition, more than 90% of the adsorbed Cu(II) and Pb(II) ions were recovered in a 1M HNO3 solution after 1 h. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 869-873, 2011