Heat capacities of the water + lithium bromide + ethanolamine (LiBr/H2N(CH2)(2)OH mass ratio = 3.5) and water + lithium bromide + 1,3-propanediol (LiBr/HO(CH2)(3)OH mass ratio = 3.5) systems were measured by using an isoperibol solution calorimeter at four temperatures (283.15, 298.15, 313.15, and 333.15 K) and absorbent (LiBr + H2N(CH2)(2)OH and LiBr + HO(CH2)(3)OH) concentration ranges of(29.2 to 70.7)% and (30.7 to 68.3)%, respectively. The measured values were fitted with a simple equation by a least-squares method and the average absolute deviations between experimental and calculated values were 0.21% for the water + lithium bromide + ethanolamine system and 0.15% for the water + lithium bromide + 1,3-propanediol system, respectively.