Binary diffusion coefficients, D-12, and partition ratios, k, for the poly(ethylene glycol) (PEG) layer to supercritical carbon dioxide for acetone and some solid solutes such as phenol, alpha -tocopherol, and beta -carotene were measured with a PEG-coated capillary column by a tracer response technique. The D-12 values for acetone with the PEG-coated column were consistent with those measured by the Taylor dispersion method in which an uncoated capillary column was employed. The D-12 and k values for all of the solutes decrease simply with increasing pressure, and the D-12 values were represented by the Schmidt number correlation.