In this paper, an original approach is presented to solve the problem of signi®cant reaction slow-down encountered in solid±gas thermochemical transformers functioning under low pressure. This approach associates a heat exchanger and a gas diuser as a single element, the `integrated thermal and mass diuser' and leads to a signi®cant gain in reactor performance, by 100% from improvements to the basic system to 200% by the use of more sophisticated systems. Various reactor con®gurations have been simulated and discussed. These served as general guidelines for new technical approaches pursued afterwards that will apply more re®ned and sophisticated simulation tools and experimental devices for the objective of heat and mass transfer enhancements. From one of the examples of a synthesis reaction under 0.2 bar, it turned out that reactors equipped with an integrated thermal and mass diuser in the middle of the reactor give the most satisfactory solution to the slow-down problem of reactor performance, with an advancement increase of 0.4. This improvement of the reactor performance is signi®cant, and leads to the industrial application of such solid±gas thermochemical transformers for cold generation at À608C.