Thermocracking products of high-sulfur Mordovo-Karmal asphalt/bitumen containing 3.7 wt. % sulfur and 6.7 wt. % ibp-200 A degrees C fraction are analyzed. Additional 8.1% ibp-360A degrees C fraction can be obtained by cracking the bitumen at 450 A degrees C for 120 min with maximum gas and coke yield totaling more than 20 wt. %. The effect of fly ash microspheres on the direction of transformations of bitumen components is studied. Bitumen cracking in the presence of 10% microspheres raises the yield of the IBP-360A degrees C fraction by 10% with a total by-products (gas and coke) yield of only 4 wt. %. Structural-group composition analysis of resins and asphaltenes of bitumen cracking products indicates significant degradation of resin and asphaltene molecules in the presence of microspheres. The average molecular mass of asphaltenes decreases by 703 amu, the number of blocks in a molecule decreases from 4 to 3, and the number of naphthene rings decreases threefold, which leads to an increase in aromaticity factor, while the quantity of aliphatic fragments and the length of substituents diminish. The average asphaltene molecule becomes more compact and aromatic structural fragments dominate.