Volatile organic compounds can be replaced by more benign alternatives, such as ionic liquids (ILs) and supercritical carbon dioxide (scCO(2)). Previously, we showed that ILs offer advantages as solvents for epoxidation reactions (Kazemi et al. Green Process Synth., 2012, 1, 509-516). In this study, the high-pressure phase behavior of ternary systems containing the epoxidation reaction compounds with ILs and CO2 is measured in order to design the reaction and subsequent separation step. The organic compounds studied are cinnamyl alcohol (reactant) and (2S,3S)-(-)-3-phenylglycidol (product), and the IL used is 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim]-[Tf2N]). Phase behavior experiments are carried out using a synthetic method in the Cailletet apparatus at five different concentrations of CO2 and temperatures and pressures up to 368 K and 12.1 MPa, respectively. Both ternary systems only show one type of phase transition. A comparison between the two systems shows that both systems behave similarly at low pressures, while the solubility of CO2 in the ternary system containing cinnamyl alcohol becomes lower at high pressures. Moreover, a comparison between the binary system of [bmim][Tf2N] + CO2 and the studied ternary systems is made. Finally, using data obtained during this work, the conditions for carrying out the epoxidation reaction in a homogeneous phase and extracting the product with supercritical CO2 in the two-phase region are determined.