AbstractVolatile compounds formed during the autoxidation of freshly refined sunflower oil at 37°, as well as those produced during subsequent heating of the oxidised oil, were concentrated by vacuum distillation and separated by gas chromatography.Twenty‐two individual aliphatic compounds (carbon chain length > 5) were identified by chromatographic retention on two stationary phases, supported by confirmatory physicochemical tests for functional group and carbon skeleton on isolated microgram amounts.Semi‐quantitative analysis, using a flame ionisation detector, demonstrated a marked preponderance of hexanal in the volatile products of low‐temperature oxidation, whereas the much greater quantity of volatiles resulting from thermal decomposition of the first‐formed hydroperoxides contained major proportions of the deca‐2,4‐dienals.The formation of the identified compounds (saturated and unsaturated aldehydes, ketones, hydrocarbons and an alcohol) can be explained in large part by accepted mechanisms for the free radical decomposition of linoleate and oleate hydroperoxides, though it is not easy to account for the quantitative aspects.