A recently proposed method called quantitative topological molecular similarity (QTMS) generated a model for the computation of the relative substituent effects on the bond dissociation enthalpies (Delta BDEs) for a set of 39 phenols. The data set includes a diverse set of substituents with monosubstituted and poly-substituted derivatives that exhibit different electronic and steric effects. Many share common structural features with already well-established antioxidants. QTMS reveals the active region of the substituted phenols and identifies the electronic descriptors that best explain the range of Delta BDEs observed. For substituents in the 4-X position ( para) we find that our model requires a correction for radical stabilization enthalpy (RSE). Application of the QTMS methodology yields an unrivalled QSAR with r(2) = 0.98 and q(2) = 0.85 for the bond dissociation enthalpies of this phenolic antioxidant data set.