AbstractIn the present study, volatile oils from Onopordum arenarium fresh flowers and stems were obtained by hydrodistillation and the non-polar aerial part hexane extract was prepared using a Soxhlet apparatus. The constituents of different organs were identified for the first time by gas chromatography equipped with flame ionization detector and gas chromatography coupled to mass spectrometry. A total of 29 and 25 compounds were identified constituting over 91.6 and 89.2% of the whole constituents from flower and stem volatile oils, respectively. Both organs were constituted mainly of long-chain hydrocarbons (23.3–36.4%) followed by oxygenated long-chain hydrocarbons (31.5–33.8%) and oxygenated monoterpenes (14.4–6.6%). The major identified compound was palmitic acid [25.5% in O. arenarium flower essential oil (EO) and 28.7% in the stem EO]. Eighteen compounds representing 80.7% of the whole constituents were identified in the n-hexane extract, which was characterized by high amounts of triterpenoids (39.6%) and dominated by lupeol acetate (19.2%) and β-amyrin acetate (10.1%). Moreover, all extracts were evaluated for antioxidant potential using 1,1-diphenyl-2-picrylhydrazyl radical assay. The obtained results demonstrated that the EOs and the hexane extract could be a new source of natural potentially bioactive molecules.