Densities, viscosities and ultrasonic velocities were measured for the two ternary liquid mixtures containing morpholine (1) + 1,4-dioxane (2) + nitrobenzene (3) or + toluene (3) at 308.15 K over the entire range of mole fractions. Thermodynamic parameters, such as excess volume (V E), deviations in adiabatic compressibility (ΔK S), free length (ΔL F), isothermal compressibility (Δβ T), free volume (ΔV F) and viscosity (Δη) were calculated and applied to the Redlich−Kister polynomial equation to determine the appropriate coefficients. The deviations of the ternary liquid mixtures from their ideal behaviour were determined from the measured and calculated thermodynamic properties. In addition, an insight into the molecular structure and possible interactions for the investigated mixtures was attempted.