Abstract Capillary supercritical-fluid chromatography (CSFC) is shown to provide high-resolution separations of a wide variety of di-, tri- and polyisocyanates, including derived products such as dimer, trimer, urea, biuret, carbodiimide, phenol-blocked, thiophosphoric, carbamate and thiocarbamate isocyanates. CSFC is superior to any other available separation technique for many isocyanates. Derivatization is not necessary with a carbon dioxide mobile phase. Significant changes in selectivity of diisocyanate separations were effected by variations in temperature and use of methyl, biphenyl and octyl methylpolysiloxane stationary phases. Operating temperatures of up to 100°C could be used. With neat carbon dioxide as the mobile phase, the applicable mass range had an upper limit of 500–2000 g mol −1, depending on sample structure and composition.