AbstractOn‐line HPLC‐HRGC coupling offers new analytical possibilities in the separation of complex mixtures. This technique has been used for the separation and identification of sesquiterpene and paraffin hydrocarbons in cold pressed citrus oils.The sesquiterpene and paraffin hydrocarbons fractions of these oils are pre‐separated in two different LC chromatographic runs, using a Hypersil 5μm(10 cm × 0.21cm i.d.) microbore column and as mobile phase, 0.2 ml/min flow‐rate,n‐pentane to isolate the sesquiterpenes, andn‐hexane to isolate the paraffins. The fractions thus separated are directly transferred on to the OV1 capillary column (22 m × 0.32 mm i.d., 0.4 μmfilm thickness), which separates the individual components.The analytical sample was obtained by a simple dilution of the oils in hexane, without any further handling; analysis time is short.The HPLC‐HRGC coupling allows a high degree of certainty in the chromatographic identification of the various components and therefore more certain information on the composition of citrus oils.The results obtained by analysing cold pressed lemon, bergamot, mandarin, sweet and bitter orange