Correlations of graph theoretical parameters with Delta H-f(o) of buckminsterfullerene and 28 proposed precursor molecules were investigated. The 29 molecules examined divided cleanly into groups of 19 and 10 structures, with Delta(f)(o) for the smaller group depending only on the number of carbon atoms (r = 0.9730). Delta H-f(o) for the larger group was successfully predicted with a two-parameter equation (r = 0.9987). One of the parameters had been used previously to predict Delta H-f(o) for all-hexagon polycyclic aromatic hydrocarbons (PAHs), but not for PAHs containing pentagons. The other parameter had not previously been used with PAHs.