The hydration of α−tricalcium phosphate (α−TCP) is known to lead to the formation of an interlinked calcium−deficient hydroxyapatite (CDHA) framework. This apatite resembles the composition and structure of physiologic bone mineral, making it a good candidate for bone reconstruction. The additional presence of a calcium sulfate phase, which has a faster resorption rate than apatite, gives a gradual creation of porosity in the cement. This may in turn enhance bone ingrowth. The aim of this study was to gain deeper understanding of the main characteristics and properties of a bi−phasic α−TCP/α−CSH cement, prepared with an X−ray contrast medium.Isothermal calorimetry has been used to follow the course of the hydration reaction over time as it involves traceable exothermic events with possible contributions from both the calcium phosphate and calcium sulfate components. This was done in an attempt to identify and differentiate the role of each reactive phase. Additionally, the total produced heat from the cement has been used to estimate the degree of conversion and this result has been verified by X−ray diffraction analysis.Furthermore, compressive strength of the α−TCP/α−CSH cement has been measured over time to investigate the possible connection to its thermal evolution signature. Also, the impact of the surrounding environment on the α−TCP and α−CSH conversion was investigated by comparing XRD results between samples that had been kept dry or wet.