The metallization of high-temperature polymers like poly(ether sulfone) (PES) is important, especially for microelectronic purposes. The adhesion of metals to these polymers can be greatly improved by using ion implantation. The low ion doses required to improve adhesion, however, make it difficult to determine the mechanism of the adhesion enhancement. This work studies the buried interfaces of ion implanted and as-deposited metal films (Al, Fe, and Cu) on PES. The U.K. Synchrotron Radiation Source at Daresbury Laboratory was used to provide tuneable photon energies in the range of 2100 eV up to 4600 eV. Thus, the interface can be probed to greater depth than usual without being destroyed by peeling or sputter profiling. Adhesion improvement as measured by mechanical testing can, thus, be linked to the chemical changes occurring at the interface of the system. These findings are complemented by additional x-ray absorption spectroscopy (NEXAFS studies) of spincoated PES films. These experiments are designed to give a deeper understanding of the interaction of individual metal atoms with the polymer surface.