Sr/MgO catalysts for biodiesel production were synthesized by the wet impregnation method. The formation of basic sites on the catalysts was investigated by thermal analysis, XRD, and Hammett indicator method. The calcination temperature and Sr/MgO molar ratio affect the structure as well as the catalytic activities. Among the catalysts tested, the best performance catalyst was prepared with a 0.10 Sr/MgO molar ratio and a calcination temperature of 600 degrees C. This catalyst had a base strength in the range of 15.0-18.4 and was also active for biodiesel synthesis at room temperature. The catalytic activities under various reaction variables were also evaluated. The biodiesel yield of 93% was achieved within 30 min from the transesterification of soybean oil with methanol at 65 degrees C using 5 wt.% loading of the synthesized catalyst and methanol to oil molar ratio of 12:1. (C) 2013 Elsevier Ltd. All rights reserved.