Polyacrylonitrile (PAN) nanofibers were produced by electrospinning, then heated to crosslink and stabilize their morphology. The properties of resultant nanofibers were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and solvent extraction. The FTIR spectra of heated PAN revealed three simultaneous reactions within nanofibers: dehydrogenation, cyclization, and carbonylation. Their stabilization kinetics was different from the microfibers. The gel fraction results of extraction in DMF indicated the crosslinking degree resulted from the heat treatment. The SEM observation confirmed the integrity of nanofibers after alkaline hydrolysis. These finely modified PAN nanofibers have potential applications such as superabsorbent and artificial muscles. (C) 2014 Elsevier Ltd. All rights reserved.