I am developing a new theoretical approach for the estimation of bond dissociation enthalpy (BDE) and bond dissociation free energy of X-H bonds by estimating the relative heats of formations of unimolecular dissociative states. The succuss of this approach very much depends on the availability of consistent experimental bond dissociation energy data, with which my theoretical results can be compared. I am particularly interested in the O-H BDE of BHT because it is one of the few hydroxylic antioxidants, for which my above-described theoretical approach slightly underestimated their BDE.