In this work, the effect of an ammonium nitrate ionic liquid on the corrosion susceptibility of an Al-Cu-Mg alloy was investigated. The effect of the nitrate anion and the ammonium cation on the anodic and cathodic kinetics were studied separately using potentiodynamic polarisation testing, electrochemical impedance spectroscopy and scanning electron microscopy. The results revealed a significant anodic inhibition, associated with a cation/anion synergy. The cathodic kinetics however increase with the presence of nitrates, associated with nitrate reduction reaction. Conversely, longer alkyl chain seemed to reduce the effect of nitrates. Such findings are promising in the context of developing ecofriendly chromate alternatives.