Small clusters modeling various surfaces of platinum are employed in relativistic molecular orbital calculations. The results are correlated with existing ultraviolet (UPS) and X-ray (XPS) photoelectron spectra. The Pt valence band consists of two complexes, d52and d32, separated by spin-orbit splitting. The UPS result for clean Pt(111) conforms to a schematic description of the Pt d-band. The calculated ionization energies for the adsorbed CO compare well with UPS and XPS data.