In the thermal diffusion separation of native crude oils, perylenes and metalloporphyrins are concentrated mainly in fractions from the lower part of the thermal diffusion column. The higher thermal diffusion fractions do not contain these compounds. The metalloporphyrin concentrates produced during the thermal diffusion separation of crude oils are enriched with homologues of the ETIO (etioporphyrin) series. Porphyrins of the DPEP (desoxophylloerythroetioporphyrin) series are mainly present in fractions from the middle part of the thermal diffusion column. The proportion of nickel complexes in the metalloporphyrin mixture increases from the lower to the middle part of the thermal diffusion column.