The binary (carbon dioxide + ethane) exhibits an unusual and interesting phase equilibrium behaviour especially in the critical region of the pure components and their mixtures. The critical line of this system was determined by using a flow apparatus. The experimental results were compared with the predictive Soave-Redlich-Kwong (PSRK) model. In this paper the PSRK model was also applied to the calculation of critical points, (vapour + liquid) equilibria, azeotropic points, excess enthalpies (H-E), excess volumes (V-E), and Henry's coefficients (H-12) The investigated systems included (carbon dioxide + ethane, or propane, or rt-butane. or n-hexadecane). In the PSRK calculations only one pair of temperature-dependent interaction parameters is required for (carbon dioxide + an n-alkane). The calculated results were compared with experimental data. The relation of excess properties with phase equilibria in (carbon dioxide + ethane) was discussed in detail.