It is generally agreed that the factors influencing permeation and diffusion hydrogen at room temperature are as follows: the thickness and surface condition of the specimen, composition, microstructure and grain size of the material, hydrogen traps and stress or strain conditions for the specimen, etc. Up to now, however, little attention has been paid to the effect of the area ratio, i.e. permeation area divided by the total area and the effect of the geometric shape a specimen. The authors found accidentally that the hydrogen permeation current could not be detected when the permeation area ratio [zeta] was smaller than a critical value, which depended upon the geometric shape. In this work, the effect of permeation area ratio and the shape on permeation and diffusion of hydrogen will be investigated in detail. Diffusion of hydrogen in copper and steel is studied.