The densities of aqueous mixtures of diethanolamine (DEA) + N-methyldiethanolamine (MDEA) + water, DEA + 2-amino-2-methyl-1-propanol (AMP) + water, and monoethanolamine (MEA) + 2-piperidineethanol (2-PE) + water were measured from 30 degrees C to 80 degrees C. A Redlich-Kister equation of the excess volume was applied to represent the density. Based on the available density data for five ternary systems : MEA + MDEA + H2O, MEA + AMP + H2O, DEA + MDEA + H2O, DEA + AMP + H2O, and MEA + 2-PE + H2O, a generalized set of binary parameters were determined. The density calculations show quite satisfactory results. The overall average absolute percent deviation is about 0.04% for a total of 686 data points.