The properties of the surface oxide film on pure iron after electrochemical passivation and thermal annealing treatments were investigated using a variety of techniques. Passivation was carried out with an applied potential of 800mV (vs Ag/AgCl) for 15min in a pH 8.4 borate buffer solution at 30°C, whilst annealing was carried out in air in an electric furnace at temperatures up to 300°C. Analysis of the surface properties was then carried out using X-ray diffraction to determine oxide composition, a spectroscopic ellipsometer to measure the optical properties and oxide thickness, and a scanning probe microscope to measure the surface roughness using tapping mode AFM and to observe the nanoscale structure using constant height mode STM.