This work reports the data of heat capacity and thermodynamic properties of crystalline layered perovskite-like oxides: the protonated titanate H2Nd2Ti3O10 and its n-butoxy derivative H2Nd2Ti3O10×BuOH in the range of (5 – 340) K. Isobaric heat capacity of the compounds was measured by precise adiabatic vacuum calorimetry. Standard thermodynamic properties of the oxides were evaluated from the experimental heat capacity temperature dependencies. On the basis of the experimental data obtained in this work, the applicability of the additivity principle for prediction of thermodynamic properties for layered organic-inorganic hybrid has been tested. As result, we found the evidence that the additivity principle is not implemented in case of the covalent bonding between inorganic matrix and organic molecules, it brings the suggestion that the impossibility to calculate the capacity of hybrid as sum of ones for oxide and organic component confirms the covalent bonding between inorganic matrix and organic component.