This paper reports the change in the bulk transport properties of p-type MCT samples induced by a rapid thermal annealing (RTA) process. This change is produced homogeneously within the crystal without interchange of mercury with the surrounding atmosphere. The carrier concentration varies towards an equilibrium value that depends only on the annealing temperature. For the material and temperatures investigated (250–420°C) the equilibrium carrier concentration depends exponentially on the inverse of the temperature, its value ranges between 1 × 1017 and 4 × 1017 cm−3. The time needed to reach equilibrium is a function of the temperature, varying from 10 s at 420°C to 200 s at 250°C. The hole mobility is also affected by the RTA process, its evolution being a function of the process temperature and time. A model is proposed to explain these modifications based on a reaction of generation-annhilitation of mercury vacancies and interstitials that would take place within the crystal with no external interaction.