Many synthesis procedures have been worked out to prepare CaSnO3. A great deal of them resort to the classical ceramic method that implies a very high temperature treatment (1300-1500 degrees C) of the component oxides mixture. To avoid such high temperature treatment, many alternative routes have been proposed. In this paper stoichiometric mixtures of Ca citrate tetrahydrate and Sn(II) oxalate have been mechanically activated by high energy milling. The reactions taking place in the mixtures during annealing have been studied by coupled TG-DSC measurements, XRPD and diffuse reflectance FT-IR spectroscopy. It has been established that the stage of mechanical activation allows the synthesis to be completed by 3 h-annealing at 850 degrees C. (C) 2015 Elsevier B.V. All rights reserved.