In this work, a batch-type reactor system was used to prepare biodiesel from RBD palm oil in supercritical methanol without any catalyst. Experiments were carried out by changing the operation parameters such as temperature (200-400 degrees C), the mole ratio of methanol to RBD palm oil (3-80) and reaction time (0.5-20 min). The content of fatty acid methyl esters (FAMEs) was analyzed using a gas chromatography by means of British standards. The content of FAMEs increased drastically with temperature above the critical point and with the mole ratio of methanol to RBD palm oil up to 30. However, the content of FAMEs was affected by thermal decomposition of RBD palm oil and FAMEs above 300 degrees C. Irreversible reaction scheme was used to examine the kinetics of transesterification of RBD palm oil. Activation energy calculated by nonlinear regression was agreed well with the published data. (C) 2007 Elsevier B.V. All rights reserved.