The solubility of stearic acid in supercritical CO2 with n-octane and acetic acid cosolvents was measured at 308.15 K in the pressure range from 80 to 160 bar and the cosolvent concentrations range from 0.0 to 3.5 mol%. The density of the fluid phase was also determined. The solubility increases with the concentrations of the cosolvents (Y-3) and pressure. However, the solubility increases very slowly with Y-3 at higher Y-3 when acetic acid is used as a cosolvent, mainly because acetic acid can associate with itself. In CO2-acetic acid mixture, the solubility increases with Y-3 provided that the apparent density of CO2 d(1) (moles of CO2 per liter of fluid) is fixed. In CO2-n-octane mixture, the solubility also increases with Y-3 at higher d(1). However, at lower d(1) and Y-3 the solubility decreases with Y-3 at fixed d(1). It was found that clustering between CO2 and the cosolvent reduces the efficiency of CO2 to dissolve the solute.