Heat capacities of three ketohexoses in monosaccharides, D-fructose, D-psicose, and D-tagatose, were measured for crystalline states in the temperature range from 13.8 K to 330 K by adiabatic calorimetry. Their standard thermodynamic functions were estimated from the measured molar heat capacities. A spectral analysis using Kieffer's model was applied to the heat capacities to rationalize the relation among them in terms of intra- and intermolecular hydrogen bond in crystal. (C) 2018 Elsevier Ltd.