Electrochemical and electrochromic behaviour of Mn + Ni hydroxides composite electrodes prepared by galvanostatic codeposition, were studied. All the composition range form 0 to 100% of Mn was analyzed and they were studied by voltammetry associated with transmittance spectra in 0.1 M KOH electrolytic solution. It was verified that traces of Mn in nickel hydroxide electrodes produce not only the shift of Ni(II)/Ni(III) redox couple towards less positive potentials but also the diminution of the oxygen evolution reaction overpotential. Optical response will be analyzed by means absorption spectra, differentiated absorbance vs. E curves and optical density vs. charge plots.