A straightforward procedure using density functional theory (M06 2X) coupled with a group-equivalent approach is described that was used to calculate gas-phase heat of formation (Delta H-f degrees(g,298)) values for buckminsterfullerene (C-60), C70 fullerene (C-70), corannulene, coronene, and sumanene. This procedure was also used to calculate exceptionally accurate Delta H-f degrees(g,298) values for a variety of single-ring aromatic and 2-7 ring polycyclic aromatic hydrocarbons (PAHs) as well as a large selection of other hydrocarbons and phenols. The approach described herein is internally consistent, and results for C-60, C-70, corannulene, coronene, and sumanene are in very close agreement with results reported by others who used higher-level computational theory. Statistical analysis of a test set containing benzene and 18 two to seven ring PAHs demonstrated that by using this approach a mean absolute deviation (MAD) and a root-mean-square deviation (RMSD) of 0.8 and 1.3 kJ/mol, respectively, were achieved for reference/experimental Delta H-f degrees(g,298) values versus calculated/predicted Delta H-f degrees(g,298) values. For statistical analysis of a larger test set containing 235 aromatic and aliphatic hydrocarbons and phenols, a MAD and a RMSD of 1.2 and 1.9 kJ/mol, 8 values. respectively, were achieved for reference/experimental Delta H-f degrees(g,298) values versus calculated/predicted Delta H-f degrees(g,298) values.