The localized corrosion behavior of Al 6061 and cast aluminum was investigated by using fluorescein in combination with fluorescence microscopy and atomic force microscopy in 0.1 M KCl solution. The formation of fluorescent rings around the inclusions can be observed within a short time after open circuit initiation of localized corrosion at open circuit. These fluorescent rings are associated with topographic features formed by precipitated corrosion products which are related to anodic dissolution sites. Hence, even a small number of anodic sites can easily be identified among a large number of inclusions. (C) 2000 Elsevier Science Ltd. All rights reserved.