The charge state of hydrogen ions in metals and semiconductors has been studied based on a comparison of hydrogen ion stopping cross-sections in metal and semiconductor targets. It is shown that neutralization of the hydrogen ion in metals and semiconductors at ion speeds νi ∼ (1-2)ν0,where ν0 = 2.2 × 108cm/s, is due to different mechanisms, i.e. to a bulk effect in metals and to a subsurface effect in semiconductors.