To increase the safety of our environments, the selection of proper building block for bio-polymer synthesis becomes vital. This research focused on determining the degree of unsaturation and reactivity of unsaturated milk bush (Thevetia peruviana) oil (TPO). The oil was extracted from Thevetia peruviana seed by Soxhlet extraction method and was further purified. Structural elucidation and characterization of purified TPO was carried out using Proton NMR spectrophotometer, Fourier transform infrared (FTIR) spectrophotometer and Gas chromatography mass spectrometer. The results revealed that the non-edible oil has a triglyceride structure, with 3.16 carbon–carbon double bonds per triglyceride which can be used as starting material to synthesized bio-polymer.