An urgent task of the oil refining industry is the development of a thermodestructive process for the processing of heavy oil residues. This paper presents the results of a study of thermal cracking of fuel oil in the presence of aluminocobaltmolybdenum regenerated spent hydrotreating catalyst. The experiments were carried out using an autoclave, as well as using a number of instrumental methods of analysis. The effect of the degree of dispersity and catalyst content on the results of the process under study was studied. The material balance of the thermal cracking process in the presence of catalyst samples of different fractional composition is compared with the material balance of thermal cracking in the temperature range of 450-470 °C. The physical and chemical properties of the samples of catalysts, raw materials and products of the process were determined. The analysis of the obtained experimental data was carried out, the conditions for the most efficient processing of raw materials in the process of thermal cracking in the presence of a catalyst were determined, and conclusions were drawn about the prospects for its use for processing heavy oil residues.