The closest environment of Al3+ cations was analyzed in detail in solutions of aluminum nitrate in the prototypical protic ionic liquid ethyl ammonium nitrate (EAN) using 1H and 14N nuclear magnetic resonance (NMR) spectra. For Al (NO3)3–EAN mixtures with different water content, a quantitative analysis of the integral intensities of the 1H and 14N signals was carried out and the composition of the first solvation shell of the aluminum cation was refined.