Magnesium sulfate is a co-product of several mining-metallurgical processing routes based on sulfuric acid leaching operations. This chemical compound, when generated and obtained as magnesium sulfate (MgSO4), is characterized as a material still without technological use by industries. However, it is known that its thermal decomposition can obtain a reactive oxide with potential use as a pH neutralizing agent as long as certain conditions are satisfied, such as a high surface area. But to satisfy these requirements, the transformation must occur at temperatures below the ones where the thermal decomposition of MgSO4 typically occurs. In this context, it is possible to reduce the decomposition temperature of magnesium sulfate through the addition of reducing agents. From this perspective, this master s dissertation aimed to evaluate the thermal behavior of different magnesium sulfate decomposition systems. The effect of the presence of carbon from coke breeze fines, solid sulfur and iron sulfate III on the decomposition of magnesium sulfate heptahydrate was studied. From the thermogravimetric analysis, it was found that C and Fe2(SO4)3 have the ability to act as good reducing agents. In both cases there was a reduction of at least 100°C in the temperature of MgSO4 decomposing. From the reactivity tests, it was found that only the decomposition product in the presence of Fe2(SO4)3 was able to act as a pH neutralizing agent, raising this quantity to values above 8.0 in 5 minutes. The characterizations of this solid material indicate that it consists of magnesium ferrites with different Fe and Mg contents.