Abstract: The present invention relates to a thermochemical system comprising a reactor, or an enclosure for storing a solid reactive material capable of absorbing a gas, the reactive material and the gas being such that, when placed together, a chemical reaction occurs which results in the gas being absorbed by the reactive material, and a reverse chemical reaction occurs, wherein the gas absorbed by the reactive material is desorbed when heating means are applied to said reactive material when the latter has absorbed the gas. Said thermochemical system is characterized in that the reactor consists of an outer housing which is made of a composite material and which contains a sealed inner housing containing the reactive material, the heating means being arranged between the two enclosures.