Abstract: In this paper the properties of the sigma-phase of Fe-Cr alloy have been stu- died at 109 K and 718 K by calorimetry. At 1093 K the σ→a phase transformn enthalpies are different from reported values~[4] and at 718 K the a→σ phase trans- formation enthalpies reported by no person have been obtained. The X-ray diffrac- tion experiments have been used to determine that no σ phase exists yet at room temperature.