In the present study, intergranular corrosion (IGC) in AA2024 and AA2099 aluminium alloys was investigated. The IGC propagation path was examined using scanning and transmission electron microscopies. Further, electron backscatter diffraction was employed to investigate the relationship between the grain structure and the IGC susceptibility. It was found that IGC could occur at grain boundaries where second phase precipitates were absent. It was also revealed that IGC occurred at the grain boundaries that surround grains of relatively high-stored energy, and corrosion was not confined within the region immediately adjacent to the grain boundaries but had developed into the grains of relatively high-stored energy, suggesting that IGC propagated within the grains that have relatively high levels of defects. Copyright © 2013 John Wiley & Sons, Ltd.