Viscosity and density data for the ternary solution of hexanedioic acid + dextran 40000 + water at the temperatures (293.15, 298.15, 303.15, 308.15, and 313.15) K have been measured. On the basis of the Eyring and Feakins equation, the viscosity B coefficients and the activation parameters for viscous flow of the solution have been evaluated. The effect of temperature and the dextran concentration on these parameters has been discussed. With an increase in the dextran concentration, the activation free energy of viscous flow first decreases and then increases. Dextran improves the hydrophobic property of hexanedioic acid. However, the interaction between dextran and hexanedioic acid makes the flowability of the ternary solution decrease.