The effects of free fatty acids and water on transesterification of beef tallow with methanol were investigated (Ma et al., 1998a). The results showed that the water content of beef tallow should be kept below 0.06% w/w and free fatty acid content of beef tallow should be kept below 0.5%, w/w in order to get the best conversion. Water content was a more critical variable in the transesterification process than were free fatty acids. The maximum content of free fatty acids confirmed the research results of Bradshaw and Meuly (1944)and Feuge and Grose (1949).