Biodiesel is a promising alternative fuel. This pilot plant study highlights the production of biodiesel from two nonedible oils, i.e. Karanja (Pongamia pinnata) oil and Jatropha (Jatropha curcas) oil, by transesterification process with methanol using KOH as alkali catalyst. Yield percentages of biodiesel obtained and its flash point ( °C), cloud point ( °C), pour point ( °C), kinematic viscosity (mm2/s at 40 °C) and other relevant fuel properties of pure and blended biodiesel were compared. The fuel properties of pure and blended biodiesel produced were found to be well within the range of ASTM specifications. The process optimization study on catalyst concentration and time to get maximum yield is presented, i.e. 1% catalyst concentration and time duration of 3 h were found to be suitable conditions to obtain the maximum yield. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.