The novel efficient procedure has been developed for the synthesis of biodiesel. The chloroaluminate ionic liquid has been selected for the synthesis of biodiesel. The catalyst was very efficient for the reaction with the yield of 98.5% when the reaction was carried out under the conditions of [Et(3)NH]Cl-AlCl(3) (x(AlCl(3)) = 0.7), soybean oil 5 g, methanol 2.33 g, 9 h, 70 degrees C. Operational simplicity, low cost of the catalyst used, high yields, no saponification and reusability are the key features of this methodology. (C) 2008 Elsevier Ltd. All rights reserved.