In order to develop a non toxic and biocompatible hydrogel system with potential ability in biotechnology, modified photo-crosslinkable hydrogel membranes based on chitosan were prepared. Using an EDC/NHS conjugation method, chitosan was chemically modified to incorporate a photosensitive alpha-cyano-4-hydroxycinnamic acid moiety with various degrees of substitutions. Fourier transform infrared spectra (FTIR), proton nuclear magnetic resonance (H-1 NMR) and ultraviolet-visible light spectra (UV-vis) were used for structural characterization of modified chitosan, The obtained membranes were crosslinked by irradiation in the ultraviolet region, where the photosensitive monomers showed maximum sensitivity. The prepared photo-crosslinked hydrogel membranes were investigated by thermal gravimetric analysis (TGA) and wide angle X-ray diffraction (WAXD). The swelling behaviors were investigated in terms of pH, time of swelling, and degree of substitution. Also, mechanical properties of the different photo-crosslinked hydrogel membranes were studied in both dry and wet conditions. (C) 2010 Elsevier Ltd. All rights reserved.