An experiment suitable for organic chemistry students is described. Biodiesel, a "green" fuel, consists of methyl or ethyl esters of long-chain fatty acids called FAMES (fatty acid methyl esters) or FAEES (fatty acid ethyl esters). A quick way to make FAMES is a base-catalyzed transesterification of oils or fats derived from plants or from animal sources. This experiment utilizes a safe, convenient basic catalyst, K[subscript 2]CO[subscript 3], anhydrous methanol, and any of several sources of oil to make biodiesel in 20-25 min. Only simple apparatus is required and the product floats on the top of the byproducts. IR spectroscopy, thin-layer chromatography, or relative viscosity are used to evaluate the product. (Contains 2 schemes.)