A bond energy-bond order (BEBO) relationship for fullerene molecules was obtained by combining density functional theory (DFT) calculations with the Morse potential. The BEBO relationship provides a simple method to calculate the individual binding energies of all the C-C bonds of fullerenes. Consequently, one can easily calculate the resonance energies of the fullerenes using hypothetical compounds with non-resonant double bonds as reference states. This approach was applied to C-60 and C-70, both of which have about 3.9 kcal/mol of resonance energy per carbon. (C) 2004 Elsevier B.V. All rights reserved.