Corrosion tests of copper, iron, zinc, and aluminium in the 5.85 percent sodium chloride containing 0.3per cent hydrogen peroxide were carried out for each metal in the solution by itself, for galvanic couples formed by two of those metals, and for contacts of these three metals, copper-iron-zinc and copper-iron-aluminium.For uncoupled metals, zinc was corroded most severly and iron was next. Copper and aluminium were less corroded. For galvanic couples, however, basic metal in a couple was corroded preferentially as predicted from the Galvanic Series chart. In the case of contact of three metals, only the most basic metal was corroded, but the other two metals were protected from corrosion. It was observed that the effect of protection by the loss of anodic metal decreased with time corresonding to decrease in corrosion current and then each metal came to be corroded independently after corrosion current reduced to zero. It was concluded that decrease in corrosion current was resulted from thickening of the hydrate film formed on the suface of metal.