Digital photography is used to follow corrosion-driven delamination at 95% relative humidity when 0.86 mol dm(-3) NaCl contacts an artificial coating defect on carbon steel loaded with an emeraldine salt (ES) of polyaniline (PAni) base layer and polyacrylate overlayer. Changes in the optical properties of the PAni layer reveal delamination proceeds via reduction of ES to leuco base (LB) with subsequent reoxidation of LB, by O-2, to emeraldine base. In deaerated environments ES is irreversibly reduced to LB. The results presented herein are consistent with previous proposals that inhibition occurs primarily via potential-mediated suppression of through-coating O-2 reduction. (c) 2006 The Electrochemical Society.