The nanoscale surface structure of surface oxide films formed on pure iron treated by UV irradiation at 3 mW/cm(2) and electrochemical passivation at an applied potential of 800 mV vs. Ag/AgCl in a borate buffer solution have been observed with scanning probe microscopy and spectroscopic ellipsometry. UV irradiation of the air-formed film decreased the film thickness, surface roughness and surface area. UV irradiation of electrochemically passivated surfaces increased the film thickness and the terrace width of the oxide film. (c) 2005 Elsevier B.V. All rights reserved.