The kinetics of the oxidation of disodium 3, 3’-dioxobi-indolin-2, 2’-ylidene-5, 5’ disulphonate (IC) by heptaoxodichromate(VI) ion in aqueous acid medium has been studied at 25±10C, I = 0.5 mol dm-3(NaCl). The reaction is first order in [IC] and [Cr2O7 2-] and a stoichiometric mole ratio of IC: Cr2O7 2- is 1:1. Variations in ionic strength and added cations did not affect the reaction rate of the reaction. The experiment rate law obtained is: -d[IC]/ dt = k[Cr2O7 2-][IC][H+]. A plausible mechanism has been proposed on the basis of our experimental results.