Ethylene-octene copolymer (EOC) and carbon black (CB) composites exhibit positive temperature coefficient of electrical resistivity (PTC). The electrical resistance of PTC materials increases with temperature1. Materials with substantial positive temperature coefficient of resistivity can be used as self-regulating heating materials, especially in places where temperature controlling electronics are hard or even impossible to implement. Self-regulating heating materials when electrically heated, reach an equilibrium temperature, because the generated power decreases with temperature increase, thus also preventing overheating. The difference of electro-thermal properties for crosslinked EOC-CB composites and non-crosslinked EOC-CB composites was investigated. The electrical resistance was measured while heating/cooling the composite as well as the temperature was measured while electrically heating the material by applying a voltage of 5 V. The crosslinked samples show a stable effect which is consistent throughout the measurements. On the other hand, not crosslinked EOC-CB sample electrical resistance is not stable. While heating it shows a linear dependence from temperature, but while holding the sample at a particular temperature, the resistance very notably drifts due to relaxation processes.