Abstract. The conversion of Calophyllum inophyllum L . oil into biodiesel using CaO Catalyst in a microwave assisted reactor catalyst through transesterification has been carried out. The transesterification process was carried out using the ratio of moles of methanol/oil, the amount of catalyst, the variation of time, and the variation of the weight of the catalyst. The biodiesel yield obtained was analyzed by FTIR and GC-MS. The results showed that the optimum biodiesel obtained was at a mole ratio of methanol/oil 1:15, the amount of catalyst was 5%, the variation of time was 60 minutes, and the variation of catalyst weight was 5%. From the results of the GC-MS test, it is known that biodiesel contains methyl 9.12-octadecadienoate, retention time 23.176 minutes, percentage 3.75% and m/z = 294; methyl 9-octadecenoate as much as 11.92% at a retention time of 23,283 minutes and m/z = 296.