Ionic liquids are a promising class of solvent exhibiting a large panel of attractive physico-chemical properties, which can be of interest for energy, electrocatalysis or corrosion protection applications. Therefore, in the context of European restriction REACH regulation towards chromate-based surface treatments for coating technologies, the ionic liquids route as an eco-friendly alternative, has become more and more considered. In fact, ionic liquids are exceptionally tunable, cost-effective, chemically and thermally stable, and can be easily incorporated into coating system. In addition, recent studies revealed promising corrosion inhibition for several alloys systems. For instance, in the context of Mg-alloys or steel protection, it has been suggested that a synergy between the ILs cation and anion occurs, providing inhibition on the cathodic and anodic reaction. However, studies were limited to few ionic liquid systems (imidazolium or phosphonium ionic liquids) and their associated corrosion mechanisms remain unclear. In this work, corrosion inhibition mechanism of an ammonium nitrate based ionic liquids (butylammonium nitrate, BAN) was investigated for a high strength Al-Cu-Mg alloys AA2024-T6. The inhibition mechanisms of the anion and the cation (coming from the ionic liquid) were investigated in diluted conditions. The anodic and cathodic kinetics were characterised using potentiodynamic polarisation testing in an aggressive environment (0.1 M NaCl) in the presence of the ILs at several concentrations, and particular attention was given on the incidence of the ILs on the pitting potential. Electrochemical impedance spectroscopy (EIS) at open circuit potential, and in the anodic and cathodic domain, was performed in order to isolate their associated mechanisms. Microstructural characterisation was conducted before and after immersion testing, using scanning electron microscopy and EXD mapping (SEM) in order to identify preferential inhibition sites as well as the elemental composition protective films.