This paper reports the possibility of using magnesia modified with strontium as a solid catalyst for biodiesel production via transesterification reaction. A synergetic effect between active Sr species and MgO support was clearly evidenced by the comparative study. Fine particles of the Sr-Mg catalysts prepared by the impregnation synthesis exhibited excellent activity as compared to bulk dense Sr() or less-active MgO alone. The high activity of the Sr-Mg catalyst could result from the new strong basic-sites generated from the solid phase reaction and the high dispersion of the active species, as suggested from characterization data. The study shows that the amount of Sr in the catalyst and the calcination temperature are crucial factors affecting the catalyst performance: the optimal preparation condition was that with a Sr loading amount of 5.0 mmol/g and a calcination temperature of 600 C. The methyl ester (ME) content of 97.3 wt.% was achieved over the developed catalyst within 30 min under the optimal transesterification conditions of methanol:oil molar ratio of 9:1, catalyst amount of 5 wt.% and temperature of 60 degrees C. The present study provides new insight into controlling the catalyst activity of magnesia modified with strontium by tailoring the preparation conditions. (C) 2010 Elsevier B.V. All rights reserved.