It is known that MgS : Eu 2+/Eu 3+ shows the most promising characteristics of any frequency domain optical storage material (Hasan et al., Appl. Phys. Lett. 72 (1998) 2373, 3399). Efficient photon-gated hole burning is observed in 4f 7–4f 6 5d 1 ZPL transition of Eu 2+ in MgS. In this study, the dynamics of hole burning and hole erasure is investigated. The dependence of the holedepth and holewidth on the burning time and the burn power levels has been experimentally studied. To explain the experimental data a theoretical model has been developed. The model shows very good agreement with the experimental data. The same model explains the behavior of the erasure and thermal cycling of holes.