The solubilities of benzoic acid in supercritical CO2 with pure and mixed cosolvent were measured at pressures from 8.0 to 23.0MPa and 328. 15Kfor pure cosolvent, and 308. 15, 318. 15 and 328. 15Kfor mixed cosolvent. The experiments were carried out by using a flow-type phase equilibrium apparatus. The effect of cosolvents, ethyl acetate, ethanol and ethyl acetate + ethanol (molar ratio 1:1) was studied at the concentration of 2.0 mol%. The results showthat the solubility enhancement follows the order: ethanol > ethyl acetate + ethanol > ethyl acetate. The measured solubilities were correlated using a modified Chrastil equation, and the calculated results are in good agreement with the experimental data.