Supercritical carbon dioxide-soil partition coefficients have been measured for naphthalene, phenanthrene, 1,2,3-trichlorobenzene, 1,2,4,5-tetrachlorobenzene, and pentachlorobenzene in loamy sand and silt loam. The partition coefficients, which ranged from 1.7 to 3.9 g(soil)/g(CO2) at 35 degrees C and 10.7 MPa, appear to be dependent on soil and chemical properties.