Catalytic conversion of un-pretreated Jatropha oil with high-acid value (13.8 mg KOH/g) to biodiesel was studied in ionic liquids (ILs) with metal chlorides. Several commercial ILs were used to catalyze the esterification of oleic acid. It was found that 1-butyl-3-methylimidazolium tosylate {[BMIm][TS]) had high catalytic activity with 93% esterification rate for oleic acid at 140 degrees C but only 63.7% Jatropha biodiesel yield at 200 degrees C. When ZnCl2 was added to [BMIm][TS], a maximum Jatropha biodiesel yield of 92.5% was achieved at 180 degrees C. Addition of metal ions supplied Lewis acidic sites in ILs promoted both esterification and transestrification reactions. It was also found that the transition metal ions performed higher catalytic activity in transestrification than the ions of Group A. Mixture of [BMIm][TS] and ZnCl2 was easily separated from products for reuse to avoid producing pollutants. (C) 2013 Elsevier Ltd. All rights reserved.