Abstract: The theories of 1.5th and 2.5th order differential polarographies for (n₁ = n₂) multistep reversible charge transfer are proposed and the theoretical polarograms were drawn with a computer.The effect of both the standard potential separation (△E⁰) and the number of electrons (n) on polarograms is carefully discussed.The reduction of Cu(Ⅱ) in 0.10 mol/L NH₄⁺Cl^-NH₄⁺OH^-was selected to test the theories and the experimental results were in agreement with the theories.

Key words: Multistep charge transfer, Differential polarography (Covolution voltammetry)