Adsorbed cyanide was observed on platinum electrodes using infrared spectroscopy. In situ spectral analyses were performed in a cyanide-free electrolyte solution following cyanide monolayer preparation according to an electrochemical procedure developed for earlier LEED and AES studies of cyanide adsorption on platinum electrodes. This approach minimized spectral interferences associated with reactive cyanide species in bulk solution and simplified the assignment of bands associated with surface species. Two forms of the adsorbed cyanide surface layer were identified. With the electrolyte solution at pH 12.5, a potential-dependent band appears at about 2058 cm-1 and is assigned to the vibrations of a surface layer of CN-. With the electrolyte solution at pH 8, a potential-dependent band appears at about 2147 cm-1 and is assigned to a surface cyanide layer in which CNH is the predominate species.