Abstract The antioxidant capacity of the essential oils isolated from the aerial parts of Lavandula luisieri, L. stoechas subsp. lusitanica, the hybrid L. stoechas subsp. lusitanica x L. luisieri, and L. viridis collected in different regions of Algarve (Portugal), as well as that of butylated hydroxytoluene (BHT), was evaluated using three different methods: free radical scavenging activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, thiobarbituric acid reactive substances assay (TBARS) and reductive potential. The chemical composition of the essential oils was analyzed by GC and GC/MS. The oils of L. luisieri were mainly constituted by 1,8-cineole (26â34%) and trans-Î±-necrodyl acetate (11â18%), only present in this lavender species. The oils of Lavandula stoechas subsp. lusitanica and the hybrid L. stoechas subsp. lusitanica x L. luisieri were dominated by fenchone (42â44%) and camphor (35â36%). Despite of the morphological resemblances of the L. stoechas subsp. lusitanica x L. luisieri with L. luisieri, no necrodane derivatives were detected in the hybrid, showing instead a major chemical similarity with L. stoechas oil. Lavandula viridis oil mainly comprised 1,8-cineole (33%) and camphor (20%). The oils of L. luisieri were the most effective as antioxidants, independent of the evaluation method used, although showing always lower antioxidant ability than BHT.