The simple equations for predictions of the density, viscosity, and conductivity of mixed electrolyte solutions were extended to the related properties of mixed ionic liquid solutions. The densities, viscosities, and conductivities were measured for the ternary solutions [C(4)mim]Cl (1-butyl-3-methylimidazolium chloride) + [C(4)mim]Br (1-butyl-3-methylimidazolium bromide) + H2O and [C(6)mim]Cl (1-hexyl-3-methylimidazolium chloride) + [C(6)mim]Br (1-hexyl-3-methylimidazolium bromide) + H2O and their binary subsystems [C(4)mim]Cl + H2O, [C(4)mim]Br + H2O, [C(6)mim]Cl + H2O, and [C(6)mim]Br + H2O at (293.15, 298.15, and 308.15) K, respectively. The results were used to test the predictability of the extended equations. The comparison results show that these simple equations can be used to predict the density, viscosity, and conductivity of the mixed ionic liquid solutions from the properties of their binary subsystems of equal ionic strength.