Thin film pyrolysis was used to thermally crack asphaltene molecules into their constituent building blocks at 500 degrees C. By using a thin film of liquid of ca. 20 mu m, the cracked products were rapidly released into a much colder sweep gas stream to quench the reactions and minimize further decomposition. The liquid products were condensed and collected, with over 91% material balance on the recovery of gas, liquid, and coke product. Simulated distillation of the condensed liquid products showed a wide range of compounds with boiling points up to more than 700 degrees C produced in various stages of the reaction. Less than 1% of the original mass of the asphaltenes was released in the form of light gases such as methane and ethane. The liquid components boiling below 538 degrees C comprised 15-20% of the initial asphaltenes, and contained a wide range of chemical structures including paraffins, olefins, naphthenes, aromatics, thiophenes and sulfides, and nitrogen-containing compounds, identified by gas chromatography-field ionization-time-of-flight mass spectrometry. The ring groups were substituted with a range of alkyl side chains. Asphaltenes from a range of different crude oils gave similar results. The recovery of the building blocks was limited by the reaction conditions, because rereaction of the heavy products generated more light fragments. C-13 NMR spectroscopy of the feed and products of thermal cracking of C-7 asphaltenes showed a 10-26% increase in the aromatic or double-bonded carbon contents of the products compared to the feed, consistent with yields of toluene-insoluble coke in the range of 50%. The diverse components in the cracked products, with paraffins accounting for a small fraction of the total mass, are consistent with a significant concentration of complex structures attached by bridges in the asphaltene fraction.