A new solid base catalyst containing Ca12Al14O33 and CaO was prepared by chemical synthesis method and was used in the transesterification of rapeseed oil with methanol to produce biodiesel. The catalyst was characterized by Hammett indicators, X-ray diffraction (XRD), infrared spectroscopy (IR), Brunauer-Emmett-Teller (BET) and scanning electron microscopy (SEM), separately. The effect of various factors was investigated to optimize the reaction conditions. The results showed that the ME (methyl ester) content reached 90% after reacting for 3 h at 65 degrees C, with a methanol/oil molar ratio of 15:1, the amount of catalyst of 6 wt.% and the stirring rate of 270 rpm. Moreover, the catalyst could be used repeatedly for at least 7 cycles with the ME content over 87%, due to its high stability. In particular, this solid base catalyst can be separated from reaction system effectively and easily, as it is insoluble in both methanol and methyl esters, which may provide significant benefits for developing an environmentally benign and continuous process for synthesizing biodiesel. (C) 2012 Elsevier Ltd. All rights reserved.