The kinematic viscosities of aqueous solutions of NaH2PO4, Na2HPO4, Na3PO4, KH2PO4, K2HPO4, and K3PO4, and of their pH-buffering ternary systems, were measured at various concentrations and at temperatures between 293.1 K and 323.1 K. Those of the single-solute solutions were correlated with concentration and temperature, and those of the ternary system with temperature, with deviations less than 1.2% and 0.5%, respectively.