Vapor liquid equilibrium (VLE) data were measured for the quaternary system containing CO2 n-dodecane (nC(12)), 1-decanol (C10OH), and 3,7-dimethyl-1-octanol (37DM10). The data were measured using a previously constructed static-analytic setup at temperatures between 308 and 348 K and pressures up to 19.2 MPa. The measured data indicated signs of a temperature inversion in the 1-decanol-rich mixtures. The relative solubility analysis revealed that the components in the 1-decanol-rich mixtures could be separated with greater ease than the components in the n-dodecane-rich mixture. The greater difficulty associated with separating components in the n-dodecane-rich mixture is likely linked to cosolvency effects which cause pinches in separation. The data were modeled in Aspen Plus, using the RK-ASPEN model. The modeling results highlighted the need for fitted solute solute interaction parameters. However, even with the inclusion of these parameters there still exists significant deviation between the experimental and predicted data. The RK-ASPEN model can, therefore, only be used to approximate VLE data for the system.