Mn-II-glycine complex in slightly alkaline solution is oxidized at a less positive potential (+0.25 to +0.6 V vs. Ag \ AgCl) where free Mn2+ ion is not oxidizable, leading to the formation of a thin uniform film containing Mn-III oxide. The film prepared by continuous cyclic scans in the potential region between +0.2 and +0.6 V exhibited an electron spin resonance (ESR) peak attributed to Mn-II(H2O)(6), but this resonance peak disappeared when the lowest potential was shifted to 0 V. From the electrochemical quartz crystal microbalance (EQCM) measurements, the film deposited anodically can be represented as (Mn2O6)-O-III[Mn-II(H2O)(6)](3) which corresponds to a structure where Mn-II in Mn5O6 ((Mn2Mn3O6)-Mn-III-O-II) is not bound to the oxygen atom in the Mn-III-O network but is coordinated with water molecules. The Mn-II(H2O)(6) in the film was suggested to be released during the reduction of the oxide matrix and oxidized to form the Mn-III-O bond at more positive potentials than +0.6 V.