Polymer coatings are widely used in industrial applications. The mechanical properties of these polymer coatings are known to vary with temperature and deformation rate. The characterization of the dynamic mechanical properties of these coatings at high temperatures via traditional uniaxial testing is challenging due often to their brittleness and small size. In this paper, the mechanical properties of polymer coatings are reported with emphasis on their dynamic mechanical properties at temperatures up to 280 °C characterized by a dynamic nanoindentation technique with a sharp indenter tip. Nanoindentation was used to characterize the mechanical response with emphasis on dynamic mechanical properties of polymer coatings enclosed in a high-temperature stage. To verify the method, the viscoelastic properties of a reference PET were also characterized by uniaxial cyclic tensile testing which exhibited an excellent agreement with the proposed technique. The proposed nanoindentation method can be applied to other polymer coatings and thin films that are used in applications at high temperatures.