The changes in general and localised corrosion rates (via gravimetric analysis and non-contact profilometry, respectively) of carbon steel are quantified as a function of time in water-saturated supercritical CO2 condition, affording particular attention to surface pitting at various stages throughout the 168-h experiment. It was observed that two distinctly different surface degradation and corrosion product precipitation mechanisms were occurring on the steel surfaces, which were believed to be influenced by the volume of condensed water. The results are supported with scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy coupled with selected area electron diffraction (SAED) measurements. (C) 2014 Elsevier B.V. All rights reserved.