A proof-of-concept study has been made to convert rapeseed oil into fatty acid butyl esters by means of microwave irradiation without using a catalyst. High conversions can be reached when the transesterification of triglycerides with 1-butanol was performed under near-critical or supercritical conditions. Microwave heating is an attractive method to perform high-temperature chemistry since the reaction mixture can be heated up considerably faster under carefully controlled conditions.