New results are communicated on the instability of anodic oxide films on titanium. It was found that an extraordinary anodic peak on the reverse scan of high voltage cyclic voltammetry plots (CV) was strongly influenced by the chemical pretreatment of the metal surface. The effects of the surface morphology, the highest potential attained in CV cycles and the scan rate on the existence and shape of this anodic peak are presented. Metal surface was characterized by SEM pictures and XPS spectra. The peak is attributed to the current outburst due to disturbance of the high electric field in the layer.