This is a study on the feasibility of biodiesel preparation from a new and promising nonedible plant, Thevetia neriifolia Juss. T. neriifolia Juss oil is a nonedible vegetable oil, which can be a substitute feedstock for traditional food crops in the production of environment friendly and renewable fuel. The transesterification reaction was carried out with methanol using sodium hydroxide as an alkaline catalyst. Various parameters like catalyst concentration, reaction time, reaction temperature, and methanol-oil molar ratio were investigated. The resulted oil was analyzed using a gas chromatography method. It was observed that the oil contains approximately 46 wt% oleic acid (18: 1), 20 wt% palmitic acid (16: 0), 15.8 wt% linoleic acid (18: 2), and 9.5 wt% stearic acid (18: 0). The highest yield (98.7 wt%) was obtained at 65 degrees C in 20 min with 0.9 wt% catalyst. The obtained biodiesel was examined using H-1 nuclear magnetic resonance and Fourier transform infrared spectroscopy instruments. The fuel properties of Thevetia neriifolia Juss biodiesel were determined and compared with Jatropha curcus L., beef tallow, and karanja biodiesel. Based on the results, Thevetia neriifolia Juss biodiesel possessed the best kinematic viscosity (4.36 mm(2)/s).