The solubility of arbutin,which is well known as an effective material for skin lightening,in a solvent mixture of ethanol and supercritical carbon dioxide was investigated[1].In this effort,the equilibrium loci of the pressure - composition and pressure - temperature were measured for the binary mixture of ethanol + CO2 system at the temperature ranging from 298.2K to 313.2K under the pressures between 2MPa and 9MPa by using the high-pressure equilibrium apparatus equipped with a variable-volume cell.The resulting pressure-temperature curve of the CO2 - ethanol binary system exhibited a typical type-Ⅰbehavior.The experimental P-x envelopes were correlated by using the Peng-Robinson equation of state to a satisfactory accuracy.Further,determination of the critical locus of T-x was followed by measuring the solubility of arbutin in the mixed solvent as a function of temperature,pressure and solvent composition.It was accomplished by measuring the cloud points of the ternary mixtures at various conditions in favor of a high-pressure phase equilibrium apparatus equipped with a variable-volume view cell.The arbutin loading was kept at 1.5wt% in the solvent mixture throughout this study and the pressure and temperature were varied up to 14MPa and 334K,respectively.For CO2 loadings less than 33wt% on the basis of ethanol,the cloud point was not observed.On the contrary,solid remained undissolved when CO2 loading exceeded 54wt%.Between these loadings steep and thus very pressure-sensitive solubility curves,which extend downward to a vaporization boundary,were found.