The most widely used process for producing biodiesel is the transesterification reaction using alkaline catalysts, due to their high reaction rates and appreciable conversion rates. Low cost catalysts (alkali, alkaline earth and transition metal hydroxides) are often used. In this work, the catalytic activity of sodium hydroxide (NaOH) in the synthesis of Jatropha curcas ethanol biodiesel was studied. Ethoxide ions, recently prepared (BINaOH) and stored under refrigeration for 12 (B12NaOH) and 24 (B24NaOH) hours were used in transesterification reactions. Each of these reactions was also conducted by means of newly produced ethoxide ions (BINaOH). The yields of each reaction condition were calculated as B12NaOH - 86.7%, B24NaOH - 99.3%, and BINaOH - 82.8%. It can be concluded that the transesterification reaction of J. curcas oil is not only adversely affected by hydroxyl ions (hydrolysis reaction) but also positively affected by ethoxide ions. The properties of flow and oxidative stability of biodiesel samples produced in each of the transesterification reaction conditions were analyzed as well. (C) 2011 Elsevier Ltd. All rights reserved.