The induced oxidation of Ce (III) is carried out in presence of As (III) using KMnO₄. The induction factor, that is the ratio of oxidation equivalent consumed by the equivalent of acceptor and the inductor, is determined under varied experimental conditions. The inductor factor (1.55) indicates the involvement of Mn (V) as reactive intermediate. The probable mechanism based on induction factor is suggested. It was concluded that As (III) titration with KMnO₄ gets influenced by the presence of trace amount of CeCl₃. The effect of added salt on induction has been studied.