The kinetics of the oxidation of iron(II) in 4 M sodium chloride solutions is second order in iron(II) and first order in dissolved oxygen.

The presence of trace concentrations of copper in the iron(II) solutions and catalysis by platinum metal sources of difference from published studies.

Rates of oxidation of iron(II) and copper(I) by peroxide under similar conditions shown to be first order in both metal ion and peroxide.

Both outer- and inner-sphere mechanisms are involved in the oxidation of iron(II).

Interpretation is supported by thermodynamic calculations and published kinetic data for the oxidation of iron(II) and copper(I) by the perhydroxyl radical.