The electrode characteristics of a silver-silver oxide electrode in aqueous KOH solutions containing hafnium chloride were investigated by potentiostatic and galvanostatic methods. At low concentrations less than 1x10(-2) M HfCl4 in 4.7 M KOH solution, the main four redox peaks on the cyclic voltammograms increased respectively and the electrode capacities as a positive electrode formed on a silver plate by the galvanostatic discharge were also slightly increased. While, at high concentrations more than 1x10(-1) M HfCl4 in 4.7 M KOH solution, the two redox peaks among main four redox peaks disappeared completely. Besides, the potential of the initial stage among the potentials of the two stages disappeared completely on a discharge process measured by the galvanostatic method and the electrode capacities due to this second stage increased remarkably.