The passivation of argon sputter-etch induced electrically active defects on Ge, Si, and GaAs surfaces by reaction with atomic hydrogen has been observed using deep level transient spectroscopy. A broad band of defect states, giving rise to non-linear Arrhenius plots, appears to be associated with the induced damage centres. Forn-type Ge andp-type Si, a 20-min exposure to atomic hydrogen at 180°C is shown to neutralize the damage created by a 5-min, 6 kV (DC), Ar gas sputter-etch. Forn-type GaAs a 1-h exposure at 250°C was sufficient, whilstn-type Si required a 1-h exposure to the hydrogen plasma at 300°C to passivate the damage. In each case, to remove the sputter-etch damage by thermal annealing required temperatures approximately 100°C higher, for periods of approximately 2 h.