The enthalpies of dilution of protocatechualdehyde p-hydroxybenzaldehyde in the aqueous sodium chloride solutions measured by using a mixing-flow microcalorimeter at 298.15 K. Densities the ternary homogeneous systems at different temperatures (293.15, 298.15, 303.15, 308.15, and 313.15 K) were also measured with a quartz vibrating tube densimeter. The homogeneous enthalpic interaction coefficients (hi(2), h(3), and h(4)) were calculated according to the excess enthalpy concept based on calorimetric data. The apparent molar volumes (V-phi(0),) and standard molar volumes (Vs) of the investigated system were computed from density data. The variation trends in h(2), and V-phi(0) fi with increasing salt were obtained and discussed in terms of the (solute + solute) and (solute + solvent) interactions. The experimental results showed that the molecular structures of protocatechualdehyde and p-hydroxybenzaldehyde, especially the number of hydroxyl groups, have evident influence on their thermodynamic properties. The thermodyynamic data obtained in this work may be helpful for exploring the structure function relationship of protocatechualdehyde and p-hydroxybenzaldehyde.