It has since been realized that sources of fossil fuel are finite and that the use of fossil fuel is degrading the environment. These have prompted the search for alternative energy sources especially those that are either carbon neutral or have significantly reduced carbon footprint. It has to be accepted that it is the aggregate of all these alternatives that will replace parts of the fossil fuels. This can then explain why studies are ongoing on various alternative energy areas. Most transesterification work found in the literature appear to deal with laboratory scale studies. For a difference therefore, the purpose of this study is to design a scalable biodiesel reactor for the transesterification of vegetable oil. Most data available in this area are proprietary and not available in the open literature. Stainless steel has been selected for the design so as to cater for both base and acid catalised processes and the reactor has been designed. Methods for determining the extra catalyst required to neutralize the free fatty acid in restaurant waste oil and testing for completion of reaction have been outlined. Precaution in handling the chemicals used in the transesterification process is recommended.