Sorption of CO2 (at 308.3 and 320.1 K in the pressure range of 0-120 bar) in different biocompatible polymers (ethyl-cellulose, carboxy-methyl-cellulose, and poly-vinyl-pyrrolidone) has been measured by a gravimetric method. The experimental data are qualitative, interpreted in terms of Gibbs free energy of mixing: in particular, the role of enthalpic and entropic effects are taken into account.