The phase behavior of polypropylene (PP) in n-pentane and n-pentane/carbon dioxide solvent mixtures has been studied using a high-pressure variable volume view cell. Cloud point pressures for polypropylene (M-w = 50,400) in near-critical n-pentane were studied at temperatures ranging from 432 to 470 K for polymer concentrations of 1 to 15 mass%. Furthermore, cloud point pressures for polypropylene (M-w = 95,400) in near-critical n-pentane were studied at temperatures ranging from 450 to 465 K for polymer concentrations of 1 to 8 mass%. Cloud point pressures were also measured for PP (M-w = 200,000, 3 mass%) in n-pentane at temperatures ranging from 450 K to 465 K. The cloud point pressures for PP (M-w = 50,400) in n-pentane/CO2 mixtures were determined for PP concentrations of 3.0 mass% and 9.7 mass% with CO2 solvent concentrations ranging from 12.6 mass% to 42.0 mass% at temperatures ranging from 405 K to 450 K. All of the experimental cloud point isopleths were relatively linear with approximately the same positive slope indicating LCST behavior. The experimental cloud point pressures were relatively insensitive to the concentration and molecular weight of polypropylene. At a given temperature, the cloud point pressure of the PP/n-pentane/carbon dioxide system increased almost linearly with increasing carbon dioxide solvent concentration (for carbon dioxide concentrations less than 30 mass%). The Sanchez-Lacombe (SL) equation of state was used to model the experimental data.