PTC-R is the abbreviation for "positive temperature coefficient-resistor". The description derivates from the fact that the electric resistance of this functional ceramic (in a certain temperature region), increases with a rise of temperature. There are plenty of active (overload protection, heater) and passive (level meter) applications fort his electrical component. By Joules self-heating in active operation a specific temperature field is created depending on the component-properties, which determines the local electrical and mechanical load. The knowledge of this temperature-field allows to record local phenomena, which cannot be resolved by the determination of integral properties like the temperature- and field-strength (varistor-effect)-depending resistance. Thermography is an ideal measurement method for this task. Within this work a suitable measurement system and evaluation methods fort he investigated parts were developed. The following key results were gained: - The by FE-Simulation in former woks predicted difference of the temperature distribution between geometrically identical weak PTCs with weak and strong varistor-effect could be approved by thermographic measurement. - The distribution of the electrical resistance is not as homogeneous as formally assumed. This was determined by thermographic measurements of total circumference of PTCs. The reason resistance inhomogenity can be explained by conditions during the sintering process.