This work aims at analyzing the microscopic features of binary solvent systems formed by a molecular solvent (dimethylsulfoxide or acetonitrile or methanol) and an ionic liquid cosolvent (ethylammonium nitrate). The empirical solvatochromic solvent parameters E T(30), π*, α and β were determined from the solvatochromic shifts of adequate indicators. The behavior of the solvent systems was analyzed according to their deviation from ideality. The study pays particular attention to the identification of solvent mixtures with relevant solvating properties. We have focused our attention on the most remarkable microscopic property of the explored systems, acidity, selecting three mixtures with particular hydrogen bond donating characteristics.