New hydrogel microspheres based on crosslinked dextran containing N,N'-diethylaminoethyl (DEAE) groups with different chemical structures have been used in adsorption-desorption studies. Bovine serum albumin (BSA) is frequently used in biophysical and biochemical studies. BSA has a well-known primary structure that has been associated with binding of many different categories of small molecules. Both adsorption kinetics and equilibrium isotherms for the adsorption of BSA on crosslinked DEAE dextran have been determined experimentally. These were only slightly dependent on the initial concentration of BSA but were considerably affected by the pH of the medium. The results fitted the Freundlich-Langmuir isotherm model for pH 6.9. The adsorption capacity factor and the adsorption equilibrium constant were obtained and mathematical modeling of adsorption, adsorption rate constants, and maximum adsorption were determined. Swelling kinetics of crosslinked DEAE dextran and optimum ionic strength, pH, and mass of hydrogel were also investigated. Desorption studies were finally determined under optimum medium conditions. (c) 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2288-2299, 2006