The thermal interaction kinetics of interfacial Si dangling bond Pb defects (Si3≡Si·) in (111)Si/SiO2, including passivation in molecular hydrogen (pictured as PbH formation) and dissociation in vacuum, is readdressed. An initial simple thermal model had concluded simple exponential decay for both processes characterised by single-valued activation energies Ef and Ed, respectively. The picture, however, is found inadequate. In the first part, the results are reviewed of a previous expanded electron spin resonance (ESR) study of the passivation step, leading to a consistent model for passivation, in which the existence of a significant spread σEf in Ef was exposed. In the present work, the results are presented of a similar study on the dissociation kinetics, providing distinct extension of the data set based on proper ESR defect density probing. Unlike previous conclusion, manifest non-simple exponential decay is exposed, which within the simple thermal model reveals the existence of a distinct spread σEd in Ed. Incorporation of this results in a consistent generalised thermal model, the solid set of data enabling unbiased extraction of the pertinent physical parameters, such as the attempt frequency kd0=(1.6±0.5)×1013s−1, close to the Si–H bending mode. The spreads in Ed and Ef are the natural manifestation of the stress-induced non-uniformity in atomic Pb morphology. The combination of both studies leads to a consistent unified picture of the Pb-(molecular) hydrogen interaction kinetics that matches underlying physical insight, based on the rate limiting reactions Pb+H2→Pb+H and PbH→Pb+H. It is evidenced that the model also applies to the interfacial Si dangling bond defects in (100)Si/SiO2.