Compared to literature results computed with other composite methods using the isodesmic reaction method, G4(MP2)-6X seems to underestimate C α -H BDEs, but BMK C α -H BDEs computed using the isodesmic reaction method agree very well with composite level literature results (??). BMK BDEs are also closer to high-level composite methods than DSD-PBE-P86/aug'cc-pVTZ+d BDEs reported by Chan et al. . DFT, especially B3LYP, underestimates BDEs compared to G4(MP2)-6X if they are computed directly. Using the isodesmic reaction method, a large part of this deviation vanishes. This highlights the error-canceling power of the isodesmic reaction method. Linear fit, R 2 = 0.997 Ideal correlation Fig. BDEs at BMK/6-31+G(2df,p) level of theory versus BDEs at G4(MP2)-6X level of theory, in kJ/mol, computed using the isodesmic reaction method. Slope and intercept of the linear fit are 1.0 and 5.5 kJ/mol, respectively. Ideal correlation refers to a line with unit slope and zero intercept.