The objective of this study was to understand the heat transfer phenomena which take place during the treatment of hydrocarbon-contaminated soils by pyrolysis under a reduced pressure. This article deals with the modelling of the different heat transfer phenomena occurring during the process operation. The model which was developed and its numerical resolution are based on the phenomena taking place in a porous medium. One of the hypotheses used is that the model is limited to the heat transfer phenomena occurring in a porous medium which only contains water as a pure liquid. In order to validate the model, the theoretical results were compared with the experimental results obtained while heating under vacuum a bed of sand containing water in a batch cylindrical reactor. A good agreement was obtained between the predicted and the experimental results.