Microsphere hydrogels made with emulsan-alginate were used as carrier for the microencapsulation of blue dextran in order to study the effect of emulsan on the alginate bead stability. Blue dextran release studies indicated an increase of microsphere stability in presence of emulsan, as a coating agent. BSA adsorption by emulsan-alginate microspheres is also enhanced 40% compared to alginate alone. XPS studies confirm the presence of BSA adsorbed on emulsan microsphere surfaces. These results are in agreement with the equilibrium adsorption model of Freundlich. Studies of BSA adsorption using non-equilibrium Lagergren second-order and intraparticle models, are suggesting a complex mechanisms of protein adsorption by chemisorption and intraparticle diffusion. Also, enzymatic release of BSA from emulsan microspheres containing azo-BSA under physiological conditions is suggests the possibility of using microspheres as a depot for pre-proteins of medical interest. (C) 2007 Elsevier Ltd. All rights reserved.