Infinite dilution partition coefficients of benzene, toluene, chlorobenzene and naphthalene in the ionic liquid, 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF6])-CO2 System were measured with a chromatographic technique. Partition coefficients for each solute increased with increasing pressure and had the trend of K-benzene(infinity) > K-toluene(infinity) > K-chlorobenzene(infinity) > K-naphthalene(infinity) at a given temperature. At pressures above 12 MPa, K-naphthalene(infinity) became one order in magnitude smallerthan that of the other components, which is attributed to the pi-pi and the imidazolium group of the ionic liquid. The Sanchez-Lacombe equation of state was found to provide adequate correlation of the data and their temperature and pressure trends. (C) 2007 Published by Elsevier B.V.