In the present work, response surface methodology (RSM) was used to optimize the biodiesel production from palm oil under supercritical ethanol conditions. Hexane was added as a co-solvent, which in turn accelerated the reaction rate and increased the biodiesel yield. This process enables simultaneous transesterification of triglycerides and ethyl esterification of fatty acids in a shorter reaction time and may reduce the energy consumption due to simplified separation and purification steps. Different process parameters including alcohol to oil molar ratio (25:1-50:1), reaction time (10-30 min), reaction temperature (260-300 degrees C) and co-solvent ratio (0.1-0.4% v/v) were optimized using response surface methodology. A mathematical model was developed for predicting the fatty acid ethyl ester (FAEE) yield. Fatty acid ethyl esters produced from palm oil were measured and analyzed using FT-IR, GC-MS and thermogravimetric analysis (TGA) methods. The fuel properties of the biodiesel produced were determined and compared to the American society for testing and materials (ASTMs) standards for biodiesel. (c) 2012 Elsevier Ltd. All rights reserved.