Chitosan acetate was prepared by the acetylation of chitosan with acetic anhydride and perchloric acid. Chitosan acetate films were cast from 5~10% yarn polymer solutions in 90% aqueous forulic acid. Fibers were wet-spun from the above solutions. From the IR spectra and ISC- NMR, we conjecture that the amino group in chitosan with formic acid upon dissolving the chitosan forms quaternary ammonium salt. The degree of acetylation increases with reaction time of chitosan, but we found that the acetylation is accompanied by chain scission. Chitosan was regenerated from the chitosan acetate by treating with sodium methoxide. The results of mechanical test of regenerated chitosan, the tensile strength and initial modulus increase and the elongation decreases with the relative humidity,