Alumina coatings were formed by electrolytic treatment on an Fe-17% Cr stainless steel functionalized by surface conversion treatment to induce a particular surface morphology, suited to anchoring the ceramic layer. As deposited, the coatings appeared amorphous. They were composed of two layers : the superficial layer was constituted only of aluminium compounds while the deep layer had a composition gradient. Heating the coated steel caused interface reactions between the electrochemically-induced deposit and the initial conversion coating compounds. These reactions act to strengthen coat adhesion to the substrate with formation of crystallized mixed oxide such as Fe(Cr,Al)(2)O-4. Moreover, Al2O3 phases appeared and acted as a barrier which prevented the thermal oxidation of the stainless steel.