The occurrence of detonation velocities in excess of the equilibrium C-J predictions in the Hydrogen-Chlorine mixture due to the chemical kinetics of the H-2-Cl(2)system is investigated experimentally and numerically. The new results conclusively determine the pathological nature of the H-2-Cl-2 system and confirm the hypothesis of Zel'dovich and Ratner (1941) and Guenoche et al. (1981) regarding the kinetics of this mixture.