Abstract <p>The article presents the results of a study of asphaltenes isolated from the liquid products of initiated cracking of two tar samples at 500°C in the presence of a calcium acetate additive. Characteristic changes in the composition of cracking products depending on the amount of the additive were shown. It was established that the formation of solid condensation products depended not only on the initial concentration of asphaltenes but also on their structure. Changes in the structural-group parameters of asphaltenes in the course of the initiated cracking of tars were studied. A distinctive feature of tar cracking in the presence of calcium acetate was that the additive promoted both the destruction of structural blocks and a significant decrease in their number in the composition of asphaltene molecules. In addition, the averaged asphaltene molecules became more compact due to the destruction of aliphatic substituents and naphthenic rings, and the fraction of condensed aromatic structures in their composition increased significantly.</p>