This article describes research to quantify the kinetics of Mn(II) and Fe(II) oxidation by potassium permanganate and chlorine dioxide; illustrates the effects of reduced metal ion concentration, pH, temperature, and the presence of dissolved organic carbon (DOC) on these kinetics; and investigates aspects of oxidation through modeling analyses. Among conclusions based on experimental results were the following: oxidation of reduced Mn(II) was rapid except at low solution temperatures; rates of Mn(II) oxidation are acceptable in the presence of humic or fulvic acids, but those acids strongly inhibit Fe(II) oxidation efficiency; poor manganese removal may be caused by inefficient capture of colloidal MnOx(s). The sequence in which oxidants are added may be an important issue for design and operation.