AbstractThe recovery of tritium from the Pb17Li blanket concerns closely the design of a fusion reactor. In the recent past some theoretical studies have been carried out with the main purpose to demonstrate the feasibility of some extraction units usually applied in chemical plants. It was demonstrated that some units, such as the droplets spray and bubble towers, were suitable for extracting tritium from the Pb17Li alloy on the basis of the known phisico-chemical characteristics of the hydrogen isotopes/Pb17Li system and those data thermodynamically deduced. For an effective design of these units the knowledge of kinetics of tritium desorption from Pb17Li was necessary.In this paper are reported the data of deuterium desorption from the eutectic Pb17Li under different operating conditions of temperature and deuterium partial pressures in the liquid Pb17Li alloy. The theoretical analysis of these data has shown that the overall desorption process is governed by the diffusion of deuterium atoms in the Pb17Li and by the heterogeneous reaction at the gas-eutectic interface of the deuterium atoms recombination.