Methoxy poly(ethylene glycol)-grafted chitosan (PEG-g-CS) was synthesized by mild Michael addition reaction of chitosan and methoxy polyethylene glycol monoacrylate. The chemical structure and degree of substitution (DS) of chitosan derivative were studied by FT-IR and (1)H NMR. Blend nanofibers of PEG-g-CS and poly(ethylene oxide) (PEO) were successfully fabricated by electrospinning and characterized by SEM, XRD, DSC and TEM. SEM images showed when the mass ratio of PEG-g-CS/PEO ranged from 4/1 to 1/2, uniform ultrafine fibers could be fabricated. XRD and DSC results confirmed the crystalline microstructure of PEO component. The core-shell structure nanofibers were observed by TEM. Besides, water resistance of glutaraldehyde crosslinked nanofibers and organic solvent resistance of original nanofibers were also evaluated through morphology analysis. (C) 2010 Published by Elsevier Ltd.