The thermal stability of the hydrogen passivation of aluminum accepters in p-type silicon carbide is investigated by annealing experiments. The passivation is done by low-energy ion implantation. Annealing is done under the influence of the electrical field in a reverse biased Schottky diode. The influence of temperature, p-type doping level, and hydrogen isotope (H-1 or H-2) on the depth profile of passivated accepters is investigated. At temperatures around 500 K, Al accepters become reactivated. In the electrical field, released hydrogen is moving as a positive ion and is able to passivate further accepters. Without electrical field, the effect is reversible. A qualitative model and an upper limit for the Al-H dissociation energy are given.