Many studies of alkali-catalyzed transesterification on the laboratory scale have been carried out. A reaction temperature near the boiling point of the alcohol (e.g., 60 °C for methanol) and a 6:1 molar ratio of alcohol to soybean oil were recommended (Freedman et al., 1984; Noureddini and Zhu, 1997). The kinetics of the alkali-catalyzed system were also studied by Freedman et al. (1986), Noureddini and Zhu (1997) and Darnoko and Cheryan (2000). Based on their results, approximately 90–98% oil conversion to methyl esters was observed within 90 min. In order to speed up the reaction, Boocock et al. (1998) suggested the addition of tetrahydrofuran (THF) as a co-solvent to minimize mass transfer resistance. After the reaction, different separation techniques to purify the biodiesel product from the other products were investigated by Karaosmanoğlu et al. (1996). In terms of the purity and yield of the biodiesel product, they concluded that the use of hot water washing at 50 °C was the best way to obtain a high purity (99%) and yield (86%) of the biodiesel product.