Electrospun poly(vinyl alcohol) (PVA) fibers rapidly dissolve in water. Their aqueous stability can be improved by annealing using a combination of controlled temperature and treatment time. The increase in aqueous stability of the PVA fibers is associated with an increase in PVA crystallinity and is defined by X-ray diffraction and the ratio of the Fourier transform infrared spectroscopy band intensities at 1141 and 1425 cm(-1). A ratio of intensity of these two infrared bands a parts per thousand yen2.5 or similar to 75% and above in the degree of crystallinity as determined by X-ray diffraction indicates fiber stability in water. Annealing treatment also results in an increase in the stiffness of the fibers. At a treatment temperature of 135 A degrees C for 4 h, the elastic modulus of the fiber increased by 80%. This information is useful when these fibers are being considered for applications in an aqueous environment such as membrane filter or tissue scaffold.