The essential oils (EOs) of the air-dried stem bark and leaves of Celtis zenkeri Engl. were extracted by hydrodistillation and characterized using gas chromatography-mass spectrometry. Twenty-three and nine compounds were respectively identified in the leaf and the stem bark EOs. Phytol (46.1%) was the most abundant compound in the leaf EO, while the major compounds in the stem bark EO were cycloeicosane (34.3%) and phytol (27.0%). The antioxidant activities of the obtained EOs were tested using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The percentage inhibition of the leaf EO (89.0%) was comparable to that of ascorbic acid (90.0%) and butylated hydroxy anisole (90.0%) at 250 µg/mL and higher than α-tocopherol (59.0%) at the same concentration. The EO of the stem bark of Celtis zenkeri Engl displayed good antioxidant activities when compared to the standard antioxidant drugs. The presence of these major constituents and the antioxidant activities of the EOs justify the ethnomedicinal uses of the Celtis zenkeri Engl. organs. Manuscript profile