Abstract: Background and Objective: Plant-derived medicines have been used in the treatment and management of human diseases. This study was aimed to investigate the antioxidant properties of ethanolic extract of Hymenocardia acida stem bark as well as its phytochemical composition using GC-MS. Materials and Methods: The stem bark of H. acida was collected within the premises of Federal University Wukari, Taraba state, washed, air dried at room temperature for one week and analyzed for antioxidant properties and phytochemical composition. Results: The following ranges for the ascertained antioxidant parameters were observed: Total antioxidant capacity (34-72 mg mL–1), Total phenolic content (115-242 mg mL–1) and total flavonoid content (70-122 mg mL–1). The following fatty acids, fatty acids methyl esters and volatile organic compounds were revealed by Gas Chromatography-Mass Spectrometry analysis of H. acida: 15-hydroxypentadecanoic acid, oleic acid, palmitoleic acid, 9-octadecenal (Z)-, Behenic alcohol, 1(3H)-iso benzofuranone, 6, 7-dimethoxy-3- [2-(2- methoxyphenyl)-2-oxoethyl, 2-(Acetoxymethyl)-3-(methoxycarbonyl) biphenylene, Heptasiloxane 1, 1, 3, 3, 5, 5, 7, 7, 9, 9, 11, 11, 13, 13-tetradecamethyl. Conclusion: This study showed that Hymenocardia acida stem bark has a broad spectrum of antioxidant activity and contains appreciable levels of bioactive compounds such as; Behenic alcohol and Oleic acid which have therapeutic applications.