A thin film electrode consisting of a mixture of iron and nickel oxides is prepared by a single route. Electrochemical deposition from Fe2+ and Ni2+ solutions on a titanium substrate and further thermal treatment at low temperature allowed obtaining a nanocomposite thin film of NiO and Fe2O3. The electrochemical studies performed on lithium cells assembled with this electrode material revealed the smallest irreversibility from first to second discharge ever reported during the conversion reactions of metal oxides at ∼0.8 V. Unlike bulk transition metal oxides, the poorly-crystalline oxidized material exhibited an unusually low discharge polarization. The 57Fe Mössbauer spectra of partially discharged and charged electrodes evidenced the reversibility of the conversion reaction with lithium and the efficiency of the recovery of the local environment of iron after the first cycle.