Radio frequency (rf) dielectrometry has been used to study the solubility and dipole moment behavior of polar compounds in supercritical fluid. The isothermic equilibrium solubility and dipole moments of acetonitrile, acetone, cyclopentadienyl manganese tricarbonyl (CpMn(CO)(3)), and copper(II) hexafluoroacetylacetonate hydrate (Cu(hfac)(2) . H2O) in near- and supercritical CO2 were measured at 313 K over the pressure range 5-15 MPa.; It was found that dipole moment values for acetonitrile, acetone, and CpMn(CO)(3) in CO2 are close to those in benzene and cyclohexane, in contrast to Cu(hfac)(2) . H2O, which has an enhanced dipole moment indicating strong interaction with carbon dioxide molecules.