This paper investigates a new route for intensification of methyl ester synthesis in Malaysia via alkali-catalysed transesterification of waste cooking oil derived from palm olein using a hydrodynamic cavitation reactor. The effects of the oil to methanol molar ratio (1:4-1:7), catalyst loading concentration (0.5-1.25 wt%) and reaction temperature (50-65 degrees C) have been investigated using an optimised plate with 21 holes of 1 mm diameter and an inlet pressure of 2 bar in a 50 L of hydrodynamic cavitation reactor assisted by a double diaphragm pump. Optimal conversion of 98.1% was achieved in 15 min in a hydrodynamic cavitation reactor with 1:6 molar ratio of oil to methanol, 1 wt% of catalyst and 60 degrees C of reaction temperature. It has been observed that a significant reduction in the optimum reaction time (about 6 fold) for transesterification from 90 min for mechanical stirring approach to 15 min for the hydrodynamic cavitation approach. Optimal yield efficiency of 12.50 x 10(-4) g/J was found using hydrodynamic cavitation and it was 8 fold higher than 1.5 x 10(-4)g/J when mechanical stirring was used. (C) 2015 Elsevier B.V. All rights reserved.