Viscosities of ammonium sulfate, potassium sulfate, and aluminum sulfate in water and water + (5 %, 10 %, 15 %, and 20 %) N,N-dimethylformamide mixed solvent have been measured at T = (298.15 and 308.15) K and at atmospheric pressure. A molality range has been studied between (0.0081 and 0.1000) mol.kg(-1). The viscosity data have been analyzed with the Jones-Dole equation, and B coefficients have been calculated. The results have been interpreted in terms of structure making/breaking behavior of these salts in water and water + DMF mixed solvents.