In order to calculate thermodynamic properties as well as VLE behaviour, an adequate equation of state is required. In the current work CoolProp is used as the main thermodynamic back-end. The option of using REFPROP is also possible in case calculations are required for mixtures in the two-phase region. Both tools use Helmholtz energy formulations for modelling pure components and mixtures. For pure CO 2 the Span-Wagner equation of state is employed , for mixtures the method of Lemmon and Kunz is used. For mixtures with CO 2 the binary parameters in both CoolProp and REFPROP have been updated with those from EOS-CG and later estimations by Herrig .