The d.c. conduction properties of partially anodized aluminium films with the oxide thickness in the range 80–200 nm were investigated using two-terminal MIM sandwich structures. The influence of the counterelectrode material, the anodic growth conditions and the post-anodization heat treatment on the current-voltage ( IV) characteristics of these oxides was also studied. It was shown that as-grown anodic films are inhomogeneous, as indicated by the observed dependence of the rectification and capacitance on the voltage in these films. Both these properties were found to be strong functions of the oxide thickness and to disappear altogether when the as-grown films were annealed at 450°C in an N 2 ambient. These observations are interpreted in terms of a model for the as-grown anodic films. The IV characteristics of annealed oxides exhibit an ohmic region and a voltage-activated region that is characteristic of the Poole-Frenkel conduction mechanism.