The effect of ultrasound power on FAME yield at different methanol to oil ratio are shown in Fig. 8. In general, increasing the methanol to oil volumetric ratio, increased the biodiesel yield (Haas et al., 2004). Also, increasing ultrasound power from 70 % to 90 % at different methanol levels showed significant effect on oil yield. At low ultrasound power levels, increasing the methanol to oil ratio from 15:1 to 25:1 increased the biodiesel yield from 80.96 % to 83.09 %. While at the same methanol to oil ratio, at high ultrasound power level, biodiesel yield increased from 85.92 % to 98.50 %. Catalyst concentration was kept constant for all trials. The statistical coefficient of determination showed a value of R²=0.96 with high ultrasound power level, while R²=0.64 with low ultrasound power level.