Aqueous biphasic systems containing ionic liquids (ILs) attract rather high attention; in particular their application in liquid−liquid extraction is very attractive due to the specificity of the systems and great possibilities in the modification of IL chemical structures. In the present work, a series of amino acid ionic liquids (AAILs) based on the 1-alkyl-3-methylimidazolium cation and L-glutamic acid anion [Cnmim][Glu] (n = 4, 6, 8) were synthesized. Densities, refractive indices, and specific electrical conductivities of aqueous solutions of these AAILs in the concentration range 0−70 wt % (for [C4mim][Glu] solutions up to 87 wt %) were measured at temperature 298.15 K and ambient pressure 0.1 MPa. The liquid−liquid equilibria for ternary solutions [Cnmim][Glu] + salt (K2CO3) + water at 298.15 K were under study. In aqueous solutions of [C8mim][Glu] micellization is observed, whereas [C4mim][Glu] and [C6mim][Glu] in aqueous solutions form small ordinary aggregates. The critical micellar concentration fo