Dynamic viscosity of binary mixtures of poly(ethylene glycol) molar mass 1500 Da + water, potassium phosphate + water, and ternary mixtures of poly(ethylene glycol) molar mass 1500 Da + potassium phosphate + water were determined at 303.15 K Binary and ternary mixture viscosities showed a direct logarithm-type relation with the increase of poly(ethylene glycol) and potassium phosphate contents. The models used for viscosity correlation gave a good fit to the experimental data.