Abstract: The most common process for making acicuiar particles of γ-Fe₂O₃ from hydrated ferric oxide α(FeO) OH involves three steps dehydration → reduction → oxidation. Mechanisms of the porefilling and the densification in the process of dehydration and conditions of phase transformation in reduction and oxidation periods have Loon investigated by means of simultaneous thermogravimetric and differential thermal analyses from the energy point of view on purpose to obtain the ideal technologicas process of heat treatment. The dense product of γ-Fe₂O₃ and coating with fewer porel and superior magnetic properties were obtained by the technological process which is better than the traditional one.