Impedance spectroscopy was used to study the corrosion of a nickel implanted steel sample. The dosaye was 5 × 1015ions/cm2and the energy of the nickel ions was 3 MeV. The data from a Simple Randies circuit (Rpand Cdl) were used to explain the corrosion changes observed in a NACE National Association of Corrosion Engineers) Brine solution (used to emulate geothermal brine conditions) at pH 2.0 and 25°C in an air saturated solution. Iron concentrations measured by Induction Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) were used to calculate corrosion rates at various time intervals. Impedance spectroscopy1,2is an electrochemical technique which can be used to monitor corrosion and to our knowledge it has not been applied to implanted materials.