Standard reduction potential (in volts) of the perhalate ions are given as below. ClO4−+2H++2e−→ClO3−+H2O E∘=+1.19V BrO4−+2H++2e−→BrO3−+H2O E∘=+1.74V IO4−+2H++2e−→IO3−+H2O E∘=+1.65V
More the standard reduction potential the more is tendency of perhalite ion to undergo reduction and more stronger it will be as an oxidising agent.