This study aims to examine methods and the most suitable conditions for producing methy. ester from crude rubber seed oil. An acid esterification-alkaline transesterification process is proposed. In the experiment, the 20% FFA of crude oil could be reduced to 3% FFA by acid esterification. The product after esterified was then traneserified by alkaline transesterification process. By this method, the maximum yield of methyl ester was 90% by mass. The yielded methyl ester was tested for its fuel properties and met requirement standards. The major fatty acid methyl ester compositions are methyl linoleate 41.57%, methyl oleate 24.87%, and methyl lonolenate 15.16%. Therefore, the cetane number of methyl ester can be estimated as 47.9, while the tested result of motor cetane number is 51.2. The engine performance tests were carried out with a small single cylinderengine at full load conditions. Testing in the engine, with neat methyl ester (B100), it was found that the torque and brake horse power of the engine using B100 were averagely 5% lower than those of the engine using diesel. The specific fuel consumption of B100 engine was averagely about 10% higher than that of diesel engine depending on engine speeds. At low engine speed, the brake thermal efficiency of the engine using B100 was higher than that using diesel by 5%. Also, it was found that the emission from B100 engine i.e. CO, and CO2 are lower than those of the diesel engine.