AbstractDeuterium was simultaneously ion- and gas-driven into specimens of nickel, 304 SS and vanadium, and its permeation rate was experimentally measured. The values of the permeation rate were used to evaluate the “recombination rate coefficient” kR. Results revealed that, under the conditions of the present study, the recombination process at surfaces was the rate-limiting step of the permeation for the metals investigated. Also, the values of kR were very sensitive to the surface impurity compositions. In such cases, treatment of the surfaces in respect to their impurity compositions was found to be effective in controlling the permeation rate.