The adsorption of 4,4'-bipyridine (BiPy) on Cu(111) has been investigated in 0.1 M HClO4 by cyclic voltammetry, electrochemical scanning tunneling microscopy (STM), and surface-enhanced infrared adsorption spectroscopy (SEIRAS). Cyclic voltammetry showed the double layer region extending from -0.2 to 0.26 V and a pair of redox waves superposing on hydrogen evolution wave at more negative potentials. Diprotonated BiPy, BiPyH22+, is adsorbed flat on the Cu(111) (1 x 1) surface and forms a well-ordered monolayer with a (3 x 4) symmetry in the double-layer potential region. At more negative potential, BiPyH22+ is reduced to its monocation radical, BiPyH2 center dot+, and forms another well-ordered structure in which the radicals are stacked in molecular rows with a face-to-face self-dimer as the building unit. The SEIRA spectra of both BiPyH22+ and BiPyH2 center dot+ are dominated by gerade modes which should be IR-inactive for the centrosymmetric species. The breakdown of the selection rule of IR absorption is ascribed to the vibronic coupling associated with charge transfer between BiPyH22+ and the surface and between the radicals.