Kinematic viscosities were measured over the entire range of composition and at atmospheric pressure for the binary systems trifluoroethanol (TFE)-H2O, TFE-tetraethylene glycol dimethyl ether (TEGDME), and TEGDME-H2O from 293.15 to 333.15 K. The data were fitted by the Stephan and Heckenbergber (1989) correlation, which accounts for the dependence on temperature and mixture composition. Methods for predicting ternary excess viscosities from excess viscosity data for the three binary mixtures involved are examined and tested for the system TFE-H2O-TEGDME at 303.15 K by comparing predicted and experimental data. The empirical correlation of Colinet (1967) is shown to be the best for this system.