Non-aromatic hydrocarbon fractions contained in the semicoking oil of two Estonian oil shales, kukersite and dictyonema shale, have been investigated using a combined chromatography-mass spectrometry technique. It has been established that the oils investigated are quite similar with respect to the qualitative composition of their hydrocarbon components, but rather different from a quantitative aspect. Alongside of n-alkanes and n-1-alkenes, which are typical for shale oils, several series of n-alkenes with a different position of double bond (specifically n-5-alkanes), dienes, isoprenoic alkanes, alkyl derivatives of cyclohexane, cyclohexene, cyclopentene and decahydronaphthalene have been detected. There is a good probability that some unusual cyclic hydrocarbons of the cyclododecane and cyclohexadecane series have been identified.