Pitting behavior in the presence of cathodic polarization was investigated using aluminum single crystals with surface orientations of (100), (110), and (111). The effects of the surface orientations on pit density, pit current density, and pit morphology were studied. In addition, the development of crystallographic etch pits was discussed in terms of the stability of the passive film and dissolution rate of aluminum. (C) 2003 The Electrochemical Society.