The influence of grain orientation on the electrochemical behaviour of iron in acetate buffer pH 6.0 was analyzed using a capillary microcel. Cyclic voltammetry and simultaneous capacity measurements were performed on the two crystal faces of an iron (100)/(111) bi-crystal, on the grain boundary between these two orientations and on several single grains of a coarse grain iron sample. The combination with electron back scattered diffraction (EBSD) yields the surface orientation of the analyzed grains and makes it possible to perform orientation dependent experiments on the polycrystalline metal. Clear differences in the electrochemical behaviour, e.g. in corrosion tendency and oxide formation rate were found between the orientations (100) and (III) of the iron bi-crystal and between several grain orientations of the polycrystalline sample. (c) 2005 Published by Elsevier Ltd.