Application of ultrasound-assisted biodiesel production process from Jatropha oil catalyzed by activated carbon-supported tungstophosphoric acid catalyst was studied. Influences of ultrasonic energy on different process variables were elucidated. Reaction variables i.e. reaction time (10-50 min), reactants' molar ratio (5:1-25:1), ultrasonic amplitude (30-90% of the maximum sonifier power) and catalyst amount (2.5-4.5 w/w oil) were studied. A mathematical representation for biodiesel yield was successfully generated. A yield of 91% was achieved in just 40 min at a moderate ultrasonic amplitude (similar to 60%), high molar ratio (25:1) and low reaction temperature (65 degrees C). Interactions between the variables were also validated statistically. Leaching study revealed that the reaction was predominately heterogeneous in nature. (C) 2012 Elsevier Ltd. All rights reserved.