In this work phase equilibrium measurements for binary systems of supercritical propane with the n-alkanes C36H74, C38H78, C40H82, C44H90, C46H94, C54H110 and C60H122, in the temperature range 378.2-408.2 K, are reported. In this temperature range the isopleths can be approximated as straight lines. A plot of the phase transition pressure as a function of carbon number at constant temperature and mass fraction yields a linear relationship. These linear relationships can be used for interpolation and limited extrapolations. The equilibrium data indicate that propane can be used for the fractionation of alkane mixtures. The SAFT EOS, using two binary interaction parameters, can be used to describe the equilibrium data provided that the temperature is not too close to the critical temperature of the solvent. The binary interaction parameters tend towards constant values for high carbon number alkanes. (C) 2003 Elsevier Science B.V. All rights reserved.