The viscosity, density, and refractive index of binary mixtures of ethyl formate or ethyl benzoate with o-xylene, m-xylene, p-xylene, and ethylbenzene were determined at 303.15 K and 313.15 K and atmospheric pressure for the whole composition range. From the experimental measurements, the deviations in viscosity, Δη, were correlated accurately with the Redlich−Kister polynomial equation. The deviations in molar refraction, ΔR, were calculated from the Lorentz−Lorentz equation. The experimental viscosities were fitted to an empirical equation proposed by Frenkel. It was observed that the equation predicts the mixture viscosities reasonably well at both temperatures and the agreement between the experimental and calculated values is satisfactory.