Abstract Recently, Wittig and co-workers have published rate coefficients k( E) for the unimolecular decomposition of photoinitiated NO 2 close to the dissociation threshold [Chem. Phys. Lett. 358 (2002) 71]. They found out that k( E) for low angular momentum J exhibits a strong increase within 25 cm −1 of the reaction threshold. The authors emphasize that their experimental results are surprising and cannot be understood quantitatively on the basis of current theory on NO 2. In this Comment we demonstrate that recent quantum mechanical calculations of NO 2 resonances on a global 3D-potential energy surface can indeed explain their data close to the dissociation threshold as well as for larger excess energies.