The densities and viscosities of aqueous mixtures of monoethanolamine (MEA) with N-methyldiethanolamine (MDEA) and MEA with 2-amino-2-methyl-1-propanol (AMP) have been studied at temperatures from 30 to 80-degrees-C. For density measurements, four MEA + MDEA (a total of 20 mass %) + H2O mixtures and eight MEA + AMP (20 and 30 mass %) + H2O mixtures were studied. For viscosity measurements, ten MEA + MDEA + H2O mixtures and eight MEA + AMP + H2O mixtures were measured. A Redlich-Kister equation of the excess volume was applied to represent the density of the liquid mixtures. The equation of Grunberg and Nissan of liquid viscosity was used to correlate the viscosity data. Both density and viscosity calculations show satisfactory results.