<p>We discuss the composition and properties of the liquid products of the low-temperature cracking of heavy oil from the Ashalchinsky field on the surface of carbonate mineral additives at 250-360°C and pressures up to 2 MPa in superheated steam with and without Al₂O₃ and MnO₂. The decomposition of the resinous-asphaltene components on the surface of carbonate minerals enhanced the proportion of low-boiling saturated and aromatic hydrocarbon products. The branching and aliphaticity of the liquid products were reduced and the aromaticity increased with increasing cracking temperature. Alcohol-benzene resins were cracked at 250°C, while benzene resins were decomposed at 300°C. Manganese oxide was found to increase the rate of the decomposition of alcohol-benzene resins and aluminum oxide-resinous asphaltene substances in general, while the content of asphaltenes in the products remained unchanged. Increasing the cracking temperature to 360°C led to the conversion of asphaltenes up to 36% along with the formation of gaseous products, volatile compounds, saturated and aromatic hydrocarbons.</p>