Accuracy of earlier reported models for predicting liquid mixture viscosity for dry and water-saturated tri-n-butyl phosphate (TBP)/n-dodecane solutions is stated to be ±20%. Interaction parameters for the popular Grunberg-Nissan model have been computed, and liquid mixture viscosity has been modeled for a binary system of dry TBP/n-dodecane as well as the ternary system of water-saturated TBP/n-dodecane solutions at 298.15 K. In addition, dynamic viscosity of TBP has been modeled on the basis of an extension of the Andrade equation for an extended temperature range of 208.15 to 338.15 K.