Analyses of rheological and small-angle X-ray scattering (SAXS) data measured using asphaltic samples that had been exposed to temperatures in the range 200-435 degrees C suggest there may be a macrochemistry involving organized groups of molecules that results in coke formation. The organized groups of asphaltic molecules form from smaller micelles naturally present in the heptane insoluble asphaltenes and from small micelles that form in the non-asphaltenic fi action above 200 degrees C. The small micelles have a characteristic length of 0.004 mu m but flocculate and then coalesce into two-dimensional microscopic particles that have a characteristic length of 0.02-0.03 mu m. It is suggested these larger particles polymerize into macroscopic particles of coke. The results of catalytic hydrocracking experiments indicate this macrochemistry can be interrupted by substances capable of preventing the low-temperature flocculation. Conversion of the 1000(+)degrees F into 1000-degrees F material is improved by 10 percentage points on addition of 1 wt % of a poly(propylene oxide)phosphidoasphaltene additive. There is also a similar improvement in the amount of desulfurization and demetalization.