Tailoring the polymer-metal interface is crucial for advanced material design. Vacuum deposition methods for metal layer coating are widely used in industry and research. They allow for installing a variety of nanostructures, often making use of the selective interaction of the metal atoms with the underlying polymer thin film. The polymer thin film may eventually be nanostructured, too, in order to create a hierarchy in length scales. Grazing incidence X-ray scattering is an advanced method to characterize and investigate polymer-metal interfaces. Being non-destructive and yielding statistically relevant results, it allows for deducing the detailed polymer-metal interaction. We review the use of grazing incidence X-ray scattering to elucidate the polymer-metal interface, making use of the modern synchrotron radiation facilities, allowing for very local studies via in situ (so-called "stop-sputter") experiments as well as studies observing the nanostructured metal nanoparticle layer growth in real time.