Partition coefficients of methyl methacrylate and acetone between some polymer and compressed gaseous carbon dioxide phases were determined by an in situ Fourier transform infrared (FTIR) spectroscopy method with a special designed high pressure IR cell at 318.2 K and 2.0-7.0 MPa. At the same temperature and pressure, the partition coefficient for methyl methacrylate was higher than that for acetone between the same polymer and subcritical carbon dioxide. For most solute/polymer/CO2 systems, the partition coefficient of solute between the polymer and compressed gaseous carbon dioxide decreased with the pressure increase. Only for a methyl methacrylate/poly(methyl methacrylate)/CO2 system, the partiton coefficient was not sensitive to the pressure change at pressures lower than 3.9 MPa. A linear solvation free energy relationship was used to estimate the main tendency of the pressure dependency. With the pressure dependent polarizability-dipolarity parameter of carbon dioxide, the calculated results were in accord with some experimental results.