In this paper, tricalcium aluminate hexahydrate (Ca3Al2O6·6H2O), thanks to its appropriate features, was assessed as an innovative, low-cost and nontoxic material for thermochemical energy storage applications. The high dehydration heat and the occurring temperature (200–300 °C) suggest that this material could be more effective than conventional thermochemical storage materials operating at medium temperature. For these reasons, in the present paper, Ca3Al2O6·6H2O hydration/dehydration performances, at varying synthesis procedures, were assessed. Experimentally, a co-precipitation and a solid–solid synthesis were studied in order to develop a preparation method that better provides a performing material for this specific application field. Thermal analysis (TGA, DSC) and structural characterization (XRD) were performed to evaluate the thermochemical behavior at medium temperature of the prepared materials. Furthermore, reversibility of the dehydration process and chemical stability of the obtained materials were investigated through cycling dehydration/hydration tests. The promising results, in terms of de/hydration performance and storage density (≈200 MJ/m3), confirm the potential effectiveness of this material for thermochemical energy storage applications and encourage further developments on this topic.