Abstract: The Pt metal is a central electrocatalyst of fuel cell. In order to study the behavior of hydrogen on the Pt surfaces, the adsorption and electrocatalytic oxidation of H ₂ on the top, bridge and hollow sites of Pt(111) surface were investigated by using density functional theory. The investigation revealed that the most favorable adsorption site was the hollow site. The adsorption energy on the electrode surface was more than that on the metallic surface. The bond length of H—H increased. The vibration frequency of H ₂ adsorbed was smaller than that of free molecular H ₂, namely, a red-shift occurs. Results show that this method can theoretically explain the adsorption and electrocatalytic mechanism of H ₂ on Pt electrode surface.