Binary diffusion coefficients D-12 and partition ratios k at infinite dilution for beta-carotene and alpha-tocopherol in supercritical carbon dioxide were measured at temperatures from 308.15 to 333.15 K and pressures from 9 to 30 MPa by a tracer response technique with a poly(ethylene glycol) coated capillary column. Both parameters, simultaneously determined by fitting the calculated response curve to that measured experimentally, were well represented with the correlations: the D-12/T values were correlated with CO2 viscosity, and the k values were expressed with a function of temperature and CO2 density. However, the partial molar volumes obtained from the k values were not well consistent with those estimated using equation of states having the interaction parameters k(ij) reported in the literature. (C) 2002 Elsevier Science B.V. All rights reserved.