A new experimental procedure for the evaluation of the partition coefficient of oligomers in supercritical carbon dioxide as a function of chain length is presented. After validating the technique through comparison with literature data, results involving polystyrene, poly(methyl methacrylate), and poly(vinylidene fluoride) are shown and discussed. The effect of chain end groups and of the presence of cosolvents is also analyzed. Most of the experiments are performed at a pressure of 150 bar and a temperature of 338 K, conditions which are typical for heterogeneous polymerization reactions carried out in supercritical media. The measured partition coefficients are well correlated by a simplified log-linear relationship proposed in the literature.