The kinetics of H sorption in a thick plate Pd\H electrode in cyclic voltammetry (CV) are studied by numerical methods and the effects of various parameters on the peak potential, peak current and hydrogen concentration are discussed. We find that the hydrogen concentration in PdHx is much less than the equilibrium value and give a simple criterion for the existence of phases occurring during CV. The voltammetric electro-sorption of H into Pd and electro-desorption of H from Pd are controlled by the adsorption of H on Pd and diffusion of H in Pd, respectively. By comparison with the previous experimental results, it is concluded that there are two sorts of adsorption, strong and weak playing key roles in H absorption into Pd at anodic and cathodic overpotentials (vs. RHE), respectively.