A static method coupled with gravimetric analysis was used to measure the solubility of L-proline in subcritical 1,1,1,2-tetrafluoroethane (HFC-134a) and supercritical CO2 (scCO(2)). The solubility Of L-proline is much higher in HFC-134a fluid than in scCO(2). The solubilities of L-proline in HFC-134a and scCO(2) are affected by temperature and pressure. The solubilities increase with increasing temperature and pressure for both scCO(2) and HFC-134a solvents. The densities of scCO(2) and subcritical HFC-134a were calculated using the Peng-Robinson (P-R) equation. Experimentally determined density data were used to assess the accuracy of the P-R equation.