H2SO4catalyzed pre-esterification of Jatropha curcas oil was investigated in this study. Ultrasound was used to enhance the mixing extent of methanol and oil. The experimental results showed that 18% methanol (wt% of oil), 1.2% H2SO4catalyst (wt% of oil) and 900 W/L ultrasonic power density were the optimum conditions for the pre-esterification of Jatropha curcas oil with a 20 mg KOH/g initial acid value (AV).The kinetics of the pre-esterification shows that the apparent forward reaction rate constant k increased with the rise of the amounts of methanol, catalyst and ultrasonic power density to some extent, while the reverse reaction rate constant was almost independent on these factors. Compared with mechanical stirring, ultrasonic radiation could greatly enhance the pre-esterification. Finally, a function of ultrasonic
power density U was embedded into the kinetic equation, and under the optimum conditions, k
A
þcould be
expressed as: k. The relative deviations between the
experimental data and the results calculated by the equation are less than 5%.