Biodiesel produced from the edible sources has the limitations of food security issues and hence not considered as a sustainable approach. Pathways based on non-edible and waste vegetable sources, which can be considered as sustainable green feed stocks, have been developed but these feed stocks contain large amount of free fatty acid and moisture which requires additional processing making the operation energy intensive and time consuming. Ample scope is available for the use of process intensification techniques with an objective of making the synthesis economically viable and one such intensification approach is based on the use of sonochemical reactors. The current work will review the basic mechanism of expected intensification, fundamentals of sonochemical reactors, different applications and finally present important design and operational guidelines for maximizing the extent of intensification. Possible combinations of sonochemical reactors with other techniques of intensification such as use of microwave and hydrodynamic cavitation will also be discussed. It has been observed that use of sonochemical reactors can considerably intensify the biodiesel synthesis process with substantial reduction in processing time and requirement of the raw materials coupled with greener and safer operation. (C) 2011 Elsevier B.V. All rights reserved.