A novel chitosan-anthraldehyde derivative film was prepared by the reaction of 79% deacetylated chitosan with 9-anthraldehyde with a hydrogel by a solution casting method. The prepared chitosan derivative film was confirmed by ultraviolet-visible absorption spectroscopy of the absorption peak at 266 nm due to the presence of an anthracene ring. The crosslinking reaction showed significant changes in the Fourier transform infrared spectrum of the chitosan derivative film. The characteristic peak of CH=N stretching bands at 1610 cm(-1) confirmed the formation of a Schiff base after the reaction of chitosan with 9-anthraldehyde. The film was evaluated by X-ray diffraction, scanning electron microscopy, photoluminescence spectroscopy, and second harmonic generation (SHG). The nature of the crystallinity of the chitosan derivative from X-ray diffraction analysis confirmed that the film may have had nonlinear optical properties. The chitosan derivative showed a redshifted emission maximum because of the electron-rich polymer main chain. No reabsorption of the second harmonic signal and no resonance enhancements were noticed during the SHG study; this indicated that the chitosan derivative possessed SHG ability. Overall, the chitosan derivative film opens new perspectives for optical material for biomedical applications. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 3056-3062,2010