The amount of substance transferred per unit time at a specified surface. Using Faraday's law, the corrosion rate, v cor, can be formally expressed as an electric current which at the corrosion potential is called the corrosion current, Icor, e.g. for the anodic dissolution of one component of a material with v cor in mol s-1 and Icor in A one obtains Icor = n.F.vcor, n being the charge number of the electrode reaction and F the Faraday constant.