The heat capacity of wood and its constituents is important for the correct evaluation of many of their thermodynamic properties, including heat exchange involved in sorption of water. In this study, the dry state heat capacity of cellulose, hemicelluloses and lignin are mathematically described by fundamental physical theories relating heat capacity with molecular vibrations. Based on knowledge about chemical structure and molecular vibrations derived from infrared and Raman spectroscopy, heat capacities are calculated and compared with experimental data from literature for a range of bio-and wood polymers in the temperature range 5–370 K. A very close correspondence between experimental and calculated results is observed, illustrating the possibility of linking macroscopic thermodynamic properties with their physical nano-scale origin.