The chromatographic impulse response (CIR) method with curve fitting was employed for measuring binary diffusion coefficients D-12 at infinite dilution for polar compounds such as benzoic acid and C-1 to C-3 mono-alcohols in supercritical (SC) carbon dioxide at 313.2 K and pressures higher than 9.5 MPa. The measured D-12 values for the polar compounds were expressed with two correlations which well represent binary diffusion coefficients for non-polar and weak polarcompounds, i.e. the correlation of D-12/Tas a function of CO, viscosity and the Schmidt number correlation. Moreover, the slope was -0.5 in logarithmic plot of D-12 versus solute molecular weight over the range of molecular weight from 32 to 1138 at 313.2 K and 11.0 MPa. (c) 2006 Elsevier B.V. All rights reserved.