Chitosan interaction with stearic, oxalic, malonic, and succinic acids and with phthalic, succinic, and maleic anhydrides under shear deformation was investigated. It was shown that under these conditions the production of cor responding chitosan derivatives takes place. On the basis of elemental analysis, potentiometric titration, and IR spectroscopy data, the possible mechanisms of the reaction are discussed. (C) 2000 John Wiley & Sons. Inc. J Appl Polym Sci 76: 616-622, 2000.