The attenuation and quenching of hydrogen-oxygen detonations transmitted across a column of cylinders were investigated experimentally and analytically at sub-atmospheric pressures. Two distinct transmission regimes were observed: successful detonation transmission and complete quenching. The transition between the two regimes was found to correlate with the ratio of inter-cylinder separation distance b to a characteristic detonation scale (cell size or induction zone length) for large blockage ratios, with critical limits comparable with those previously reported for detonation diffraction from slots. Based on available cell size measurements, the critical transmission limit was \(b/\lambda =4.5\pm 3\) . The proposed theoretical model based on Whitham’s geometric shock dynamics confirmed the equivalence between the detonation diffraction at abrupt area changes and around cylinders with large blockage ratios. Complete quenching observed experimentally was accounted for by the weak shock strength of the transmitted shock upon detonation failure. For the tested blockage ratios, the speed of the transmitted shock ranged between 50% and 60% of the Chapman-Jouguet detonation speed. This resulted in shock temperatures below the cross-over regime for hydrogen ignition, leading to very long ignition delay times even with the Mach reflection increasing the temperature. The very long ignition delay time suppressed auto-ignition, while the high isentropic exponent prevented further convective mixing required for re-initiation. This explained the fundamental difference between the arrest of hydrogen detonations and other hydrocarbons, for which transmitted fast flames punctuated by auto-ignition events were always observed. The strength of the transmitted shock was found to be well-predicted by our previous self-similar multiple discontinuity gas-dynamic model. Over a very narrow range near the critical conditions, both hot spot re-ignition and detonation re-initiation from Mach shock reflections were observed.