Abstract Ionic liquids (ILs) offer the remarkable possibility of the direct synthesis of Eu²⁺-doped nanophosphors in solution, under atmospheric conditions, without the necessity of a high-temperature post-synthetic reduction from its trivalent oxidation state. This work uses for the first time in situ luminescence measurements for monitoring the solvation process of Eu²⁺ from the solid salt to the IL and its stability against oxidation under atmospheric conditions. Upon the addition of EuBr₂ to 1-butyl-3-methyl-imidazolium tetrafluoroborate, the formation of the solvation shell is detected by the shift of the emission band at approximately 24 100 cm⁻¹ assigned to the 5d→4f electronic transitions of Eu²⁺ within EuBr₂ to approximately 22 000 cm⁻¹, assigned to Eu²⁺ within BminBF₄, tracking the time-dependent influence of the Eu²⁺ coordination environment on the crystal field splitting of its d orbitals. Even though the solubility of EuBr₂ was demonstrated to be improved by reducing the concentration and increasing the temperature to 60°C, the performance of reactions at room temperature is recommended for future synthesis of Eu²⁺ materials in ILs due to the slight oxidation to Eu³⁺ observed upon heating.