The interaction between water and reduced ilmenite samples as produced in a hydrothermal reduction process has been investigated at temperature of 1070 and 1223 K utilizing a Ugine‐Setaram Thermobalance coupled with a mass‐spectrometer. The experimental data show that the process of oxidation of reduced ilmenite is feasible at high temperature giving rise to the formation of FeO and Fe2O3at different stages of oxidation. The process occurs according to the reactions: Fe(s), TiO2(s) (reduced ilmenite)+H2O(g)=FeO(s)+TiO2(s)+H2(g) and 2 FeO(s), 2 TiO2(s)+H2O(g)=Fe2O3(s)+2 TiO2(s)+H2(g). The oxidative process has been investigated as a function of water partial pressure in an argon carrier and as a function of the granulometry of the powder. An analysis of the residue before and after the oxidation process shows some peculiarities in the morphology of the condensed phase that will be discussed in the paper. © 2004 American Institute of Physics