[Co(30 angstrom)/Pt(x angstrom)](20) multilayers with the Pt layer thicknesses varying from 5 angstrom to 20 angstrom were characterized structurally by high angle X-ray diffraction, X-ray reflectivity, X-ray absorption spectroscopy and magnetically by X-ray magnetic circular dichroism. It is found that the structure and magnetic properties of Pt have a strong correlation with the Pt layer thickness. The 20 angstrom thickness Pt layer is not almost influenced by the adjacent Co layer and the nearest neighbors are dominated by Pt-Pt shells. With decreasing Pt layer thickness, the nearest neighbors are gradually dominated by Pt-Co shells and the Pt-Co intermixing regions also remarkable increase at the interfaces, especially for the 5 angstrom thickness Pt layer. The orbital and spin magnetic moments as well as the ratio m(orb)/m(spin) all decrease systematically with increasing Pt layer thickness, indicating that the interface atoms are polarized by direct Pt-Co hybridization, but that the adjacent layers are polarized by Pt-Pt interactions. (C) 2011 Elsevier B.V. All rights reserved.