in subcritical water–methanol method for biodiesel production, a high molar ratio of alcohol to biomass is required. According to Ayhan, higher molar ratios of methanol to waste cooking oil resulted in greater ester production in a shorter time under supercritical condition indicating that excess methanol shifted the equilibrium in favor of products. He et al. also showed that increasing the proportion of methanol enhanced the production yield effectively during the continuous transesterification of vegetable oil using supercritical methanol in a tube reactor. They found that when the molar ratio of alcohol to oil was lower than 20, fatty acid methyl esters yield increased rapidly with increasing molar ratio; when this molar ratio was between 20 and 40, the tendency of increasing was mild; and when the molar ratio was above 40, the yield of fatty acid methyl esters was constant at around 78%. This is in agreement with the results obtained in this work when biomass was directly reacted with methanol and water under subcritical condition.