Vapor-liquid equilibria (VLE) and distribution coefficients (K-values) of carbon dioxide (CO 2 ) - ethanol - water ternary systems and CO 2 - ethanol - water - flavonoid (flavone, 6-methoxyflavone or 7-hydroxyflavone) quaternary systems were measured with a flow type apparatus at (313 to 353) K and (10 to 20) MPa. CO 2 - ethanol - flavonoid ternary systems were measured at a nominal range of temperatures and pressures. The K-values of all flavonoids increased with increasing pressure. It was also indicated that the K-values of relatively lipophilic components such as flavone and 6-methoxyflavone increased with increasing water composition in feed while those of relatively hydrophilic components such as 7-hydroxyflavone increased with increasing ethanol composition in feed. A simple dimensionless relationship in terms of the K-values of the solvents (K CO2 , K EtOH , K H2O ) and the entropy-based solubility parameters of the vapor and liquid phases was developed to correlate the K-values of the three solutes in the CO 2 - ethanol - water systems over the full range of conditions studied.