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.