The present thesis deals with the surface modification of boron nitride particles in order to change their surface polarity and to allow for an application in composite materials for high voltage applications. The prerequisite for a successful industrial production process of epoxy based composite systems is a similar surface polarity, respectively surface energy, of all components involved. Due to that a surface modification of the boron nitride particles is necessary. The first approach was the coupling of trialkoxy groups of an organosilane to the particles’ surface. The intention was to modify the overall polarity of the boron nitride through specific silane head groups. The functional head groups were chosen to adjust the polarity and to provide an interface for covalent coupling of the resin matrix to the filler particles. The second approach was based on coating boron nitride with a metal oxide to increase the polarity, and to facilitate the silylation of the surface via more accessable hydroxyl groups. The success of modification was proven by FTIR and REM/EDX measurements. In addition, the quantity of the immobilized modification reagents was determined via TGA analysis. These modification strategies offered the opportunity to manufacture composites comprising the modified boron nitride particles, sheet silicates and an epoxy resin system, which can be used in high voltage applications with increased thermal conductivity as a final target.