Magnetite is an iron oxide composed of ferrous-ferric oxide, because of its magnetic properties is used in different areas. In literature there are proposals of reaction mechanisms for the formation of magnetite when it is produced electrochemically, however, these do not seem to be very clear since there are inconsistencies in their formulation. In electrochemical synthesis metallic iron is used as a cathode and as an anode in an electrolytic solution, the necessary potential is applied to oxidize iron to form magnetite (Fe3O4). The most stable oxidation state of iron is (III), some authors report that they oxidize to iron III and later reduce one part to iron II to form magnetite. One of the reported inconsistencies is the existence of solids that are formed in the anode that later diffuse to the cathode to be reduced to form the magnetite, other authors support the fact that magnetite is formed in the solution and that the hydrogen is one of the main reactants. In this work we propose a simple mechanism for the formation of magnetite:

Fe_s + 2(OH^-) →Fe(OH)_2ads+2e^-

3Fe(OH)_2ads+ 2(OH^-)→ Fe(OH)₂•2Fe(OH)_3ads+2e^-

Fe(OH)₂•2Fe(OH)_3ads →Fe₃O₄+4H₂O

This mechanism was proposed to be analyzed by EIS with the reaction mechanisms approach. This approach consists of formulating the impedance expression, starting with charge and mass balances using mathematical models, to be able to use this approach it is necessary to have intermediaries adsorbed in the mechanism. With this approach it is possible to obtain a simulated spectrum as a function of the potential by means of theoretical assumptions of the parameters involved, which can be sustained experimentally.