In this work, the use of a differential aeration technique (split-cell) to assist understanding of contributions to the corrosion of an aerospace aluminium alloy is demonstrated. The setup comprised two similar specimens immersed in differentially aerated test solutions and coupled by a zero resistance ammeter. The individual electrochemical responses of the coupled specimens during linear polarization were interpreted in relation to the aeration condition, alloy composition and surface preparation. Further, the same setup was employed to investigate corrosion inhibition by observing the current and potential transients after inhibitor addition to the aerated or deareated compartment. It was found that the split-cell technique provides detailed understanding of the corrosion process in multiphase alloys and provides important information on inhibitor performance.