Adsorption of acrylonitrile (ACN) on Cu(110) surface was investigated by infrared reflection absorption spectroscopy (IRAS), Auger electron spectroscopy (AES), and temperature programmed desorption (TPD). Two types of adsorbed ACN species on the Cu(110) surface were observed by IRAS. Initially adsorbed ACN on the Cu(110) surface was assigned to the species with the CN bond perpendicular to the surface. Another adsorbed ACN (θ<1) was parallel to the surface with the CN bond. On heating up to 520 K, the adsorbed ACN decomposed to desorbed H 2 and residual carbon and nitrogen species.