The introduction of nickel atoms in Chemical Manganese Dioxide (CMD) is studied as an alternative route for the stabilization of the structure of these solids. X-ray diffraction data evidence the incorporation of nickel in different proportions in the poorly crystalline beta/gamma-MnO2 structure of these materials. Step Potential Electrochemical Spectroscopy (SPES) of lithium anode cells using the nickel-modified solids as cathode material shows a significant improvement in the electrochemical performance upon cycling.