In this work, we report the experimental values of densities, viscosities, and refractive indices at 298.15 K and atmospheric pressure for the ternary and associated binary mixtures of tris(2-hydroxyethyl) methylammonium methylsulfate + water + ethanol. Excess molar volumes and viscosity logarithm variations have been calculated from the density and viscosity of these mixtures. The excess properties have been fitted with two polynomial models that produced acceptable correlations.