Surfaces of poly(vinyl methyl ether) (PVME), poly(vinyl methyl ketone) (PVMK), and poly(methyl methacrylate) (PMMA) were covered with different thicknesses of nickel with a metal-vapor-condensation method, and the metal-polymer interfaces were analyzed by X-ray photoelectron spectroscopy. In the very first steps of the metalization, it was found that a systematic degradation of the polymer surface occurs through CO or CO2 losses, depending on the polymer functionalities. Then, at the interface with the polymer, the condensed metal reacts by oxidization with the oxygen atoms that are still available after the surface degradation. Nickel oxide is then formed at the interface, whatever the nature of the initial polymer functional group. These new oxide species are not chemically bonded to the polymer structure, and their formation is not affected by the type of bond existing between oxygen and carbon atoms in the original polymer. Finally, the accumulation of metal on the substrate induces an amorphization of the polymer carbon structure because thermal energy is transferred from the metal coating to the polymer.