Abstract: Living microplanktonic blue-green alga Oscillatoria tenuis has been cultured in the laboratory as experimental material. The chemical analysis showed that the weight of liposoluble organic matter in O. tenuis was 5.8% of dry cell and the amounts of pigments were more over than those of aliphatic hydrocarbons. The distribution of hydrocarbons in O. tenuis indicated that a dominance of normal alkanes between n-C14 and n-C19, while a maximum at n-C17.The pigments, such as demagnesium chlorophyll a, β-carotene and an unknown orange-red pigment have been measured in the alcohol fraction and benzene fraction of liposoluble compounds on column chromatography. The research of liposoluble compounds, especially aliphatic hydrocarbons in blue-green algae is valuable to understand them as original materials for the organic matter found in ancient sediments.

Key words: Oscilloria tenuis, Liposoluble compound, Hydrocarbon, Pigment