Biodiesel is an environmentally friendly fuel, which can be used in an unmodified diesel engine. The current commercial process for biodiesel production usually proceeds via the base catalyzed transesterification of triglycerides with methanol. There is interest in developing new processes that would produce biodiesel at a lower cost. Non-catalytic processes, typically at supercritical conditions, are among those being investigated. In one such process for catalyst-free biodiesel production, triglyceride is first hydrolyzed to free fatty acids. These are then esterified to make biodiesel in the second step. We have investigated this second step by studying the esterification of oleic acid with ethanol. The experiments were conducted in quartz tube batch reactors to ensure the absence of unintentional metal catalysis, which has occurred in other studies. The samples were analyzed by high pressure liquid chromatography (HPLC). We explored the effects of temperature, phase behavior, molar ratio of ethanol to oleic acid, and water content in the feed mixture and used these results to determine the kinetics of the reaction. Three different conditions were used; 250oC f = 0.05, 250oC f = 0.26, and 230oC f = 0.56. The variable f is the fraction of the reactor that we fill with reactant. Low values of f lead to mostly gas phase systems at the reaction temperature. Likewise, high values of f lead to liquid phase reactions. The results showed that 90% conversion was achieved for 250oC f = 0.05 at 60 minutes. Lower conversion (80%) for the same temperature at higher loading was obtained at the same reaction time. For the lower temperature, 230oC, only 70% conversion was observed even at a longer time of 80 minutes. These results indicate that conversion increases as temperature increases and the reaction does not require high pressure to be completed. It may be possible to do the non-catalytic esterification well below the critical pressure, which could lead to a lower cost process. The molar ratio of alcohol to oil is another important variable in the esterification reaction. Since the reaction is reversible, more alcohol will drive the reaction to produce more product. Five different ethanol to oleic acid molar ratios (1:1, 3:1, 5:1, 7:1, and 10:1) were compared for all three reaction conditions (250oC f = 0.05, 250oC f = 0.26, 230oC f = 0.56) at a reaction time of 40 minutes. At the stoichiometric ratio (1:1), low conversion was observed as expected. We obtained 50% conversion for 250oC f = 0.26 and 230oC f = 0.56 and a slightly higher conversion of 60% for 250oC f = 0.05. For 230oC, the conversion was highest at 3:1 and the conversion decreased as the molar ratio increased. At 250oC, the conversion increased by 20% when the molar ratio increased to 3:1 and 5:1, respectively, for f = 0.05 and f = 0.26, respectively. Adding more ethanol did not have a significant impact on the conversion. The water content in the reactant mixtue was also investigated, since water is a product of this reversible reaction. The experiment was conducted at five different water contents (1%, 3%, 5%, 10%, and 15% by volume). The conversion was compared at a reaction time of 30 minutes and molar ratio of ethanol to oleic acid of 10:1 for every case. The results show that the reaction is sensitive to the water content especially for 250oC f = 0.26. Adding only 1% water results in a decrease in conversion by 10% and more than 20% decrease resulted with 5% water content. The same trend was observed for 230oC f = 0.56 but the decrease in conversion started at 3% water content. At 250oC f = 0.05, the reaction is more tolerant to water content. The conversion did not change significantly up to 3% water. The conversion decreased by 20% at maximum water content studied here. This research work shows that the esterification of oleic acid can be done non-catlytically at conditions milder than supercritical. The optimal condition is 250oC, f = 0.047, a molar ratio of 3:1 and with less than 3% water in feed. In addition, to presenting experimental results, we will report the kinetics of esterification and the importance of metal catalysis for this reaction.