The thermodynamic properties of polylactones and thermodynamic paramet
ers of reactions of their formation by polymerisation of lactones base
d on calorimetric data in the range of 0 K to 400 K are discussed. The
recommended values of thermodynamic parameters are presented. The reg
ularities and peculiarities of the thermodynamic properties and the pa
rameters of polymerisation reactions of lactones, their dependence on
the composition and the structure of reagents, physical states, and te
mperature under standard pressure are described.