Ethanol is renewable in nature and it is preferable to prepare biodiesel; a renewable fuel with the use of all renewable ingredients. However, production of biodiesel with bio-ethanol is relatively little more complex than compared to using chemical methanol. Here an attempt has been made for the transesterification of jatropha oil with anhydrous and aqueous ethanol through optimization of various process parameters such as catalyst concentration, reaction time and temperature. With anhydrous ethanol, the separation of glycerol layer from the biodiesel phase was found somewhat difficult with selected process variables. Entire mixture was looked like homogeneous liquid for the selected settling time of 12 hrs and even till 72 hrs with anhydrous ethanol. No separation could be found with catalyst concentration level upto 1.0%. It was also clearly observed that, with increased catalyst amount the yield of Jatropha ethyl ester (JEE) also increased and the highest yield 82.3% was observed with 3.0% catalyst concentration. . However the corresponding viscosity of jatropha ethyl ester was observed 7.6 cSt, which is not in acceptable range as per the BIS standards. It is seen that in respect of viscosity and yield of ester, the results are very much symmetrical for the all the process chains and increasing yield of jatropha ethyl ester was observed with increasing purity of ethanol. This extensive experimental process optimization study for the production of jatropha ethyl recommends reaction time of 75 minutes, reaction temperature of 60ºC, molar ration of 6:1, and catalyst concentration of 3.0% with ethanol purity 85%.