Gelatin, well known as a biocompatible polymer, was dissolved in formic acid and gelatin nanofiber was successfully prepared by the electrospinning using gelatin-formic acid dope solution. Stability of the dope solution was evaluated by measuring viscosity change with time. Even though the viscosity dropped markedly after 5 h, the spinnability and morphology of gelatin nanofiber were not affected at all. The parameters, such as electric field, spinning distance, and concentration of dope solution, were examined for studying the effects on electrospinnability and morphology (size, size distribution, uniformity, bead formation, etc.) of gelatin nanofiber web. The gelatin nanofibers, in the mean size of 70-170 nm, could be prepared by controlling the dope concentration under proper conditions. The electrospun gelatin nanofiber exhibited a mixture of alpha-helical and random coil conformation, which was amorphous structure with very low crystallinity. The structural transformation, from a helical (alpha-helix and triple-helix) to random coil conformation, might occur when formic acid was used for the dissolution of gelatin in electrospinning. (c) 2005 Elsevier Ltd. All rights reserved.