The H2 was dissociatively adsorbed as on-top, bridging, and threefold on Ru/MgO and Ru-Cs(+)/MgO (FTIR: Fourier transformed Infrared). The adsorption and displacement reaction of N2 were suggested to be inhibited by direct repulsion with H(a) on Ru/MgO, and direct and indirect (through H(a)) effects by doped Cs(+) on Ru-Cs(+)/MgO.