Catalyzed oxidation kinetics of dissolved Fe2+ ions to Fe3+ over active carbon in concentrated H2SO4-FeSO4 solutions was studied with isothermal and isobaric experiments carried out in a laboratory-scale pressurized autoclave. The experiments were performed at temperatures between 60 and 130 degrees C, and the pressure of oxygen (O-2) was varied between 4 and 10 bar. The kinetic results revealed that the oxidation rate was enhanced by increasing the temperature and pressure and that the catalytic and noncatalytic oxidations proceed as parallel processes. A rate equation was obtained for the catalytic oxidation process, based on the assumption that the oxidation of Fe2+ with adsorbed oxygen is rate determining. The rate equation for the catalytic oxidation has the simplified form r = k " c(Fe)c(O) (0.5)(K-O" c(O)(0.5) + 1) where c(Fe) and c(O) are the concentrations of Fe2+ ions and dissolved oxygen, respectively, and k " and K-O" are experimentally determined kinetic parameters. The total oxidation rate was simulated by including a previously determined rate equation for the noncatalytic oxidation into the global model, from which the kinetic parameters of the catalytic oxidation rate were determined. A comparison of the model fit with the experimental data revealed that the proposed rate equation is applicable for the prediction of the Fe2+ oxidation kinetics in acidic ferrous sulfate solutions.