The passivation and dissociation process of the hydrogen‐Si donor complex in plasma‐hydrogenated GaAs was presented. The temperature dependent values of dissociation frequencies &ngr;dwhich the first‐order kinetics permit, satisfy the relation &ngr;d=5.7×1013 exp(−1.79±0.05eV/kT) s−1for the no‐biased anneals. During electric‐field‐enhanced anneal experiments, we confirm that no in‐diffusion from the passivated region to the bulk is observed in the temperature ranges below 150 °C, and that there is a dissociation frequency region independent of the annealing temperature. Finally, from the electric field annealing experiment on the passivated donor inn‐type GaAs, it is suggested that the hydrogen atom in Si‐doped GaAs exposed to the plasma hydrogen is negatively charged with the gain of free electrons and passivates the Si donor, and also that the hydrogen atom or the electron of the hydrogen‐Si donor complex can be easily released by the electric field.