Saturated hydrocarbon biomarkers (n-alkanes, isoprenanes, pregnanes, steranes, cheilanthanes, hopanes) in the soluble part and thermolysis products of the insoluble part of the biomass of Thermoplasma sp. archaea isolated from the Neftyanaya Ploshchadka hot spring of the Uzon volcano caldera (Kamchatka, Russia) have been identified by gas chromatography-mass spectrometry. The distribution of these hydrocarbons resembles that of slightly transformed marine oils generated in argillaceous-carbonate strata, a fact that is confirmed by Rock-Eval pyrolysis data for the biomass of the archaea studied.