Heat capacities of aqueous mixtures of diethanolamine (DEA) with 2-amino-2-methyl-1-propanol (AMP) were measured over the temperature from 30 to 80 degreesC with a differential scanning calorimeter (DSC). For mole fractions of water ranging from 0.2 to 0.8, 16 concentrations of the DEA + AMP + water systems were studied. The binary system DEA + AMP with nine various concentrations were also studied. The heat capacities of aqueous mixtures of DEA with AMP presented in this study are, in general, of sufficient accuracy for most engineering-design calculations.