The DTA and DSC curves of Mg-2[Ti-2(O-2)(4)(OH)(4)]. 4H(2)O were recorded and used to determine isothermal conditions suitable for obtaining the intermediate samples corresponding to the phases observed during the thermal decomposition. The samples were identified by quantitative analysis,IR spectroscopy and X-ray analysis. The experimental results were used to propose a mechanism of thermal decomposition of the investigated compound to MgTiO3. The optimum conditions were also determined for obtaining MgTiO3 with well-defined crystallinity.