The growing concern for environmental preservation combined with the possibility of depletion of energy obtained from fossil fuels has driven industry to develop alternative fuels from renewable resources and environmentally non-aggressive processes. Biodiesel is an important alternative fuel whose properties are similar to those of petrodiesel. Catalysts containing Mg/La (Mg/La molar ratio =9:1) were prepared by coprecipitation using three methods that differed according to precipitating agent, and calcination temperature. The catalyst prepared with (NH4)(2)CO3/NH4OH as precipitating agent and calcined at 450 degrees C presented the best physicochemical and catalytic properties. Catalysts based on Mg/Al and Al/La with different chemical compositions were synthesized under the selected conditions. The catalytic behavior of these materials for transesterification of soybean oil with methanol was investigated and the catalysts with M/La molar ratio equal to 9:1 (M = Mg or Al) showed the best catalytic performance. Catalytic tests were also carried out in the presence of acid soybean oil. It was verified that the catalysts used have sites capable of catalyzing esterification and transesterification reactions. (C) 2015 Elsevier B.V. All rights reserved.