The kinetics of oxidation of tellurium(IV) by [IrCl6]2 in aqueous perchlorate solutions at a constant ionic strength of 0.1 mol dm3 have been investigated spectrophotometrically. The results showed a firstorder dependence in [IrCl6]2, fractional-first-order kinetics with respect to tellurium(IV) concentration and second-order overall kinetics. The increase in the [H+] was found to be accompanied by a decrease in the rate constants, i.e., the oxidation reaction was acid-inhibited. Kinetic evidence for the formation of a 1 : 1 intermediate binuclear complex between the two reactants has been obtained. The ionization constant of tellurium(IV) has been evaluated and found to be 1.69  103 dm3 mol1 at 25 1C. The kinetic parameters have been calculated and a tentative reaction mechanism consistent with the kinetic data is suggested.