A simple technique offering high biodiesel yield and quality was proposed. Palm oil and ethanol were used as raw materials, while ethyl acetate was used as a reactive cosolvent to enhance the biodiesel production performed in a microtube under supercritical conditions. On the basis of the observation, the dominant role of ethyl acetate in this work was to improve the homogeneity of the reacting mixture rather than to produce triacetin. The analysis showed that the relationship between biodiesel content and process variables including reaction temperature, residence time, ethanol-to-oil molar ratio, and mass ratio of ethyl acetate to oil was statistically significant. The interaction between the molar ratio of ethanol to oil and the mass ratio of ethyl acetate to oil was found negligible. High quality and yield of our biodiesel were obtained with the low requirement of residence time and ethanol-to-oil molar ratio, whereas the high reaction temperature was a trade-off. According to the response surface methodology, the optimal operating conditions with a fatty acid ethyl ester (FAEE) content of 98.5% were achieved at a reaction temperature of 370 degrees C, molar ratio between ethanol and oil of 16:1, residence time of 5.2 min, and mass ratio between ethyl acetate and oil of 0.2:1. Finally, superior biodiesel performance was realized through our new and simple technique.