An experimental study of the ferric oxidation kinetics of pyrite was conducted under controlled redox potentials of 700, 800 and 900 mV (vs. SHE). The rate of pyrite oxidation strongly depends on redox potential, increasing fivefold when redox potential is increased by 100 mV. Pyrite dissolution is significantly affected by temperature. Activation energies of 56.6, 55.9 and 51.9 kJ/mol calculated from pyrite dissolution at redox potentials of 700, 800 and 900 mV (vs. SHE) respectively confirmed a chemical or an electrochemical rate-determining reaction on the pyrite surface.