The present thesis deals with temperature resistant epoxy resins that can be used for insulations of high voltage generators. The processing of these resins is done by vacuum pressure impregnation (VPI). In addition to a full characterization and advancement of epoxy/anhydride resins, a resin system for cationic curing was developed. This resin system is based on a copolymerization of epoxy and aromatic vinyl components, which are polymerized at elevated temperature with metal complexes as initiators in the presence of phenolic co-initiators. The thermal curing behaviour was assessed by spectroscopic and thermoanalytical methods, moreover the shelf-lifetime and the latency of these resins was investigated. Model insulation composites with mica were prepared with the VPI process on a laboratory scale, and characterized in terms of their thermal, thermomechanical and dielectric properties. The influence of the individual resin components on the properties of both the cured and uncured resins were studied in detail. In addition to thermal curing, the radiation induced curing of these cationic resins was investigated (e-beam, X-ray and gamma ray curing). In this case, a photoacid generator was used to initiate the curing reaction. It is shown that under appropriate processing conditions the epoxy conversion and the thermomechanical properties are comparable to those obtained in a thermal curing process. This provides the possibility to cure high voltage insulation composites at significantly lower temperatures than in conventional processes.