Modelling of corrosion has developped to become a precious prediction tool, providing a useful complement to extrapolation of experimental data in order to prevent systems failure. However, it remains presently difficult to develop a comprehensive modelling covering all aspects and processes in corrosion. Such modelling would require simultaneous description of large space and long time scales, characteristic of the systems and their durability as well as atomistic scale description for chemical or electrochemical reactivity and/or atomic scale structure features such as defaults or intergranular structures.