Heat capacities of ethylamine + water + lithium bromide (H2O:LiBr = 2:1 mass) were measured using a twin isoperibol calorimeter devised for high-pressure measurements in the range of temperatures from 313.15 K to 373.15 K and in the range of ethylamine concentrations from 0 to 50.3 mass %. An empirical equation of the heat capacity for this ternary system was obtained as a function of temperature by a least-squares method from experimental data. Maximum and average absolute deviations between the experimental data measured and the calculated values from this empirical equation were 0.3% and 0.1%, respectively.