Polymer-ceramic nanocomposites are very important materials for microelectronics industry. Their synthesis typically involves the incorporation of ceramic nanoparticles as filler into a polymer matrix, providing a heterogeneous nanofiller/matrix interface structure that could play a crucial role in determining their unique properties for various applications. This chapter provides a concise account of the characterization of various polymer-ceramic nanocomposites using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dielectric and electric measurements. In addition, this chapter highlights the critical role of properties of the polymer-ceramic nanocomposites for their microwave and electrical applications with respect to their individual components that may provide valuable implications for the development of novel polymer-ceramic nanocomposites with advanced properties. © Springer Nature Switzerland AG 2021.