The densities and viscosities of aqueous blends of piperazine (PZ) with N-methyldiethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP) have been measured at (288, 293, 298, 303, 308, 313, 318, 323, 328, and 333) K. The total amine mass fraction in all solutions was kept at 30 % in view of recent interest in using concentrated amine solutions in gas treating. Correlations for the density and viscosity of the ternary mixtures are presented as a function of temperature and amine concentration.