A method has been devised whereby the Auger spectra of films formed under electrochemical conditions can be examined without damage to the film in the transfer from the electrochemical situation. The conditions do not remove water molecules from the film at room temperatures. Application of the method to the passive film on iron shows that this film differs radically in its Auger spectra from that of an air‐formed oxide film, or of the passive film after it has been heated to 150°. The change in spectrum from that of the air‐formed oxide is associated with the presence of water molecules in the structure of the passive oxide. Examination of the relative intensities of the Auger spectra suggests one water molecule per two iron atoms. The change at 150° results from the removal of this water molecule. The results are consistent with a passive film which is a hydrated ferric oxide with a gel‐like structure.