[en] PAC measurements at ¹¹¹In, yielding information on the amount of formed In-H pairs, and four point resistivity measurements were combined to study the correlation between pair formation and electrical deactivation of acceptors in p-Si samples during passivation with H and thermal reactivation. Passivation was performed by means of low energy (200 eV) H⁺ implantation which proved to be quite efficient at 400 K. A complete passivation of the In profile with a peak concentration of 10¹⁸ cm^-3 could be achieved. The results show, that the deactivation and reactivation of the In acceptors quantitatively coincide with the formation and dissociation of In-H pairs. (orig.)