Ultraviolet photodesorption of CO and CO+ from Pt(111) at 80 K is investigated by (2+1) resonance-enhanced multiphoton ionization and reflection absorption infrared spectroscopy. Desorption of CO and CO+ occurs at the on-top site as single-photon and three-photon processes, respectively. The rotational, vibrational, and translational temperatures of desorbed CO are approximately 130, 3700, and 2000 K, which are considerably higher than the sample temperature. The threshold energy of neutral CO desorption lies between 2.3 and 3.5 eV suggesting that an unoccupied 2 pi state is responsible for the desorption.