The phase behavior of blends containing chitosan with poly(vinyl-alcohol) (PVA) and poly(2-hydroxyethyl methacrylate) (P2HEM) was analyzed. Blends were obtained by casting from acetic acid solution (HAc) and 1,1,1,3,3,3 hexafluoro-2-propanol (HF2P) and studied by DSC, FT-IR, and TGA. The phase behavior of the blends of chitosan with PVA and P2HEM, studied by DSC, shows that the systems behave as one-phase systems in HAc as well as in HF2P according to the DSC results. According to the results of FT-IR analyses of the different absorptions of the blends, relative to the pure components, they show an important shift that is considered evidence of an interaction between the components of the blends. The thermogravimetric analysis of the blends and the pure components shows that the temperature for thermal degradation of the blends is higher that that of the pure components, irrespective of the solvent casting from which the mixture was obtained. These results are interpreted as the formation of a new product that corresponds to a compatible polymer blend. The compatibilization of these systems is attributed to strong interactions, like hydrogen bonds formation between the functionalized polymers and chitosan, due to the presence of interacting functional groups in all the polymers studied. (C) 2005 Wiley Periodicals, Inc.