Quaternary spinels doped with chemically modified chromium oxide (mCrO(2.65)) LiCryMn2-yO4 with y = 0.02, 0.05 and 0.1 completely stabilize the spinel structure. Cyclic voltammograms of pure spinel exhibit high irreversibility compared with that obtained initially. The spinel doped with chemically modified chrome oxide mCrO(2.65) causes the peak separation to decrease contributing to the electrochemical reversibility of the doped cathode material. Negligible shift of the peak potentials was observed for these cathodes. Chromium dopant enhances the mass transfer of Li+ in the active material. The Li+ diffusion coefficient in LiCr0.1Mn1.9O4 estimated from an analysis of the Warburg impedance is two order of magnitude higher than that in pure spinel.