The relative viscosities of a series of homologous tetraalkylammonium halides Me₄NBr, Me₄NCl, Me₄NI, n-Pr₄NCl, n-Pr₄NBr, n-Pr₄NI, Et₄NI and n-Bu₄NI in a series of ethanol-water mixtures have been determined at 30, 35 and 40 ℃. The viscosity data have been enterpreted in terms of viscosity A- and B-coefficients calculated from the Jones-Dele equation, η_r = 1+A（C）^-1/2+B․C. The energies and entropies of activation for viscous flow have also been calculated for a number of ionic species.
The results indicate that the structure breaking effect of halide ions are maximum at 0.1-0.2 mole fraction ethanol. Strucure breaking effects decease in the order I^->Br^->Cl^-.
The viscosity B-coefficients of these salts are all positive and increase in the order Me₄N⁺<Et₄N⁺<n-Pr₄N⁺<n-Bu₄N⁺ and decrease in the order for the halide C1^->Br^->1^-. The B-coefficient of Me₄NX increases and that of Pr₄NX decreases with increase in temperature. The energy and entropy of activation of these salts are calculated and the influence of such ions upon the binary solvent structure is discussed.