Platinum carbonyl complexes, Pt+(CO)(n), are generated using laser vaporization and probed with infrared photodissociation spectroscopy in the C-O stretching region. No fragmentation is observed for the n = 1-3 complexes, indicative of their high binding energies. Pt+(CO)(4) has enhanced abundance in cluster growth and is difficult to fragment, producing a noisy spectrum. The Pt+(CO)(5,6) complexes fragment efficiently, producing the n = 4 ion. Their spectra, with carbonyl absorptions blue-shifted similar to 10 cm(-1) with respect to free CO, represent the resonances of Pt+(CO)(4) detected by elimination of weakly bound external ligands. Pt+(CO)(4) is indicated to have filled coordination and a high symmetry structure. (C) 2008 Elsevier B. V. All rights reserved.