This research was focused on the study of delamination phenomena in metal-polymer laminates used in containers. The selected material was an electrolytic chromium coated steel (ECCS), protected by polyethylene teraphthalate (PET). The study employed an acetic acetate medium, which has been proved to degrade the PET coating depriving it from its protective capacity. The experiments consisted of electrolyte induced delamination of the PET by anodic-cathodic polarisation. The main objective was to investigate the degradation mechanisms in order to explain how the presence of electrochemical activity in the delamination cross-section front detaches the PET coating and leads to subsequent propagation of this delamination. Finally, specific delamination models were proposed for the electrochemical conditions investigated, and the degradation was characterised by SEM. The induced delamination experiments applied to the ECCS-PET composite in an acetic acetate medium allowed to discriminate between the delamination processes proper for anodic polarisation and those for cathodic polarisation.