A crude rubber seed oil which containing cyanogenic glycoside – a toxic substance cannot be used as food resources. Moreover, a high free fatty acid in the crude rubber seed oil makes it difficult to preserve as well as to further chemical modify. Therefore, the rubber seed oils are mostly utilized to feed livestock and produce fuel and soap. In order to expand the application of the rubber seed oil, it is necessary to reduce the acid value of the rubber seed oil as lower as better by removing the free fatty acid or converting them into other neutral compounds. Esterification of the crude rubber seed oil can help transform the free fatty acid into esters. In this work, the acid esterification of the crude rubber seed oil was studied and the effects of the main variables involved in the process, reaction temperature, amount of catalyst, time and the molar ratio alcohol/oil, were analyzed. Furthermore, the acid value of the product was also substantially affected by the types of catalysts and alcohols. The acid value of oil was considerably decreased from 47.6 mgKOH/g to 1.12 mgKOH/g when the esterification was carried out at 60oC, 1000 rpm, a CH¬3OH to oil molar ratio of 7:1 and 0.6 wt% H2SO4 catalysts.
