This article describes the conversion of sunflower oil into biodiesel by transesterification using microwave heating. In order to further reduce the time for reaching the fixed temperature, experiments were carried out in the presence of different pebbles: glass beads, ceramic pieces, carborundum. The quality of biodiesel obtained has been tested by means of a gas chromatograph. The results indicate that microwave heating and the use of carborundum have effectively decreased the reaction time: from 540 s without pebbles to 90 s with carborundum. (C) 2011 Elsevier Ltd. All rights reserved.