Electrospinning of chitosan solutions with poly(ethylene oxide) (PEO) in an aqueous solution of 2 wt% acetic acid was studied. The properties of the chitosan/PEO Solutions, including conductivity, surface tension and viscosity, were measured. Morphology of the electrospun chitosan/PEO was observed by using scanning electron micrographs. Results showed that the ultratine fibers could be generated after addition of PEO in 2: 1 or I : I mass ratios of chitosan to PEO from 4-6 wt% chitosan/PEO solutions at 15 kV voltage, 20 cm capillary-col lector distance and flow rate 0.1 ml/h. During electrospinning of the chitosan/PEO solutions, ultrafine fibers with diameters from 80 nm to 180 urn were obtained, while microfibers with visually thicker diameters could be formed as well. Results of X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and differential scanning calorimeter exhibited the larger electrospun microfibers were almost entirely made from PEO, while the electrospun ultrafine fibers mainly contained chitosan.