Theoretical analysis of hydrogen permeation through metal sheets has been studied by a simulation program that takes into account the diffusion and entrapment of hydrogen with various kinetic conditions. The simulations have revealed the domains of the dimensionless parameters at which the traps have significant influence on the permeation curves. The change in breakthrough time and the shape of the permeation curves are discussed for particularly important cases. The method described has been compared with the conventional t(0)-test used for the rating of enamel-grade steels and the scope of a more quantitative test has also been outlined.