The present invention relates to the field of heat treatment of a product to be dehydrated, such as sludge from a waste water treatment process. The present invention relates more particularly to a method and to a facility for drying such a product, making it possible to implement a hydrothermal carbonization operation on reactor 1 followed by a filtering and drying operation, preferably on a heating filter press 6. In order to dry said product in the heating filter press 6, a heat-transfer fluid from a heat exchanger 2 is made to flow in said heating filter press. The heat exchanger 2 is arranged so as to transfer, to the heat-transfer fluid, at least some of the heat contained in the product to be dehydrated that is output from the reactor 1.