Abstract Ferric sulfate is one of the most important reagent used in hydrometallurgy for dissolution of metal sulphides. The leaching of minerals depends upon the re-oxidation of Fe2+ to Fe3+ and recycling of the reagent. The oxidation of ferrous iron plays an important role in either commercial leaching operations or natural weathering of sulphide minerals. Iron oxidation rates observed in natural acid mine drainage highly exceed the rates found in experiments performed under sterile conditions in laboratory. This is due to the catalytic action of iron oxidizing bacteria which are usually present in such natural environments. This work presents the kinetic study of chemical (abiotic) oxidation of ferrous sulfate to ferric sulfate with molecular oxygen. For an initial ferrous iron concentration in the range of 0.08-0.64 M, temperatures in the range of 288-323 K and pH ? 2, the Fe2+ oxidation rate was found to be well described by the rate expression -dFe2+/dt = 1.26 ? 107 [Fe2+]2 PO2 exp (-72000/RT).