A procedure has been investigated for the synthesis of biodiesel from Jatropha oil using a series of pyridinium ionic liquids as catalysts. The results show that [BSPy]CF3SO3 ionic liquid exhibits the best catalytic activity among these catalysts. The yield of esters and the conversion of triglycerides reached 88.5 and 95.1%, respectively, when the reaction was carried out under the following conditions: molar ratio of oil/alcohol/catalyst, 1:18:0.15; temperature, 100 degrees C; and time, 6 h. Further study showed that the catalyst exhibited constant activity for six successive trials after being recycled. The main fuel properties of the final product meet the ASTM standards.