Squalene is applied in various fields of application. In contact with oxygen, it reacts to compounds with undesirable properties. Therefore, squalene often is hydrogenated to squalane, which is stable. Hydrogenation can advantageously be carried out with the additional application of supercritical carbon dioxide, which serves as a promoter for transporting hydrogen into the liquid phase and enhances equilibrium concentrations for squalane and squalene in the gaseous phase. In this paper, measurement and correlation of the relevant phase equilibrium data of the quaternary system are reported for search of optimized reaction conditions. In addition to literature data, VLE data are presented for the systems CO(2)-squalane, CO(2)-squalene, H(2)-squalane, CO(2)-H(2)-squalene, and CO(2)-H(2)-squalene-squalane, in the temperature and pressure ranges of (310 to 350) K and (150 to 350) bar. The quaternary system CO(2)-H(2)-squalene-squalane and all subsystems can be correlated with cubic equations of state. For this work, the program Package PE, available from the Institute for Thermal and Separation Processes, Hamburg University of Technology, was used, applying the Soave-Redlich-Kwong equation of state (SRK-EOS) with the Mathias-Klotz-Prausnitz (MKP) mixing rule. On the basis of measurements and on literature data, it is possible to correlate the experimental data and predict phase behavior in the process relevant ranges.