Volatile constituents of plants also known as essential oils have been known and used by man through ages. Essential oils were extracted from air-dried leaves of Thevetia peruviana (TP) and Hura crepitans (HC) through hydro-distillation using Clevenger-type apparatus. The extracted oils were analysed using Fourier Transformed Infrared (FTIR) and Gas chromatography/Flame ionization Detection (GC/FID) spectrometry techniques. The bioactivity of the oils was tested against five (5) bacteria isolates: Salmonella typhi, Staphylococcus aureus, Pseudomonas aeruginosa, Xanthomonas axonopodis and Streptococcus bovis and three (3) fungi species: Fusarium oxysporum, Colletotrichum gloeosporioides and Cercosporazeae-maydis. GC-MS results revealed that forty-four (44) compounds were present in each of the samples. The prominent compounds present in HC essential oil were beta-pinene (30.78 %) and nerol (31.29 %) while 1, 8-cineole (38.62 %) and linalool (32.89 %) were the major compositions of TP essential oil. Activity against bacteria and fungi species range between 6 mm to 14 mm and 5 % to 26 % respectively which was confirmed theoretically using Spatan-14 software. Thus essential oils from TP and HC could be potential sources of pharmaceutical. Key words: Thevetia peruviana, Hura crepitans, essential oil, bioactivity.
