Biodiesel is a renewable and alternative fuel which is non toxic and biodegradable. It is prepared from virgin or used vegetable oil, waste vegetable oil, byproducts of edible oil like fatty acids, stearin, etc. and animal fats through trans esterification. It is used as an automotive fuel for diesel engines as standalone or can be blended with conventional diesel without any modification in the automobiles. Use of Biodiesel causes substantial reduction of un burnt hydrocarbons, carbon mono oxide and particulate matter compared to conventional diesel resulting in lesser pollution. It has no sulphur and has 10% in built in oxygen which helps in complete combustion, thus increasing the mileage.