The thermochemical properties of ozonides, prepared from two polybutadiene rubbers of different structure, are studied via differential scanning differential scanning calorimetry. An estimation is made of the enthalpy of the thermal decomposition (=370 kJ/mol), the activation energy (90–120 kJ/mol) and the reaction order (=0.73). On the basis of the differences in the respective values of some parameters characteristic of the kinetics of the thermal decomposition, it is suggested that the cis-ozonide species exhibit higher thermal stability in comparison with the trans-form. © 1992, Taylor & Francis Group, LLC. All rights reserved.