The nanoparticle materials have been intensively studied in recent decades aiming mainly at the medical fields. In particular, nanoparticles of magnetite, Fe3O4, because it has physical and magnetic properties compatible with in vivo applications. However, even if the magnetite has low toxicity, it is necessary that the particles are coated with biocompatible material. In this work, Fe3O4 nanoparticles coated by a polymer blend of polyethylene glycol/polyvinylpyrrolidone (type core/layer) were analyzed. It was performed to study the thermal degradation of the polymer coating layer aimed at understanding the nature of the forces involved in adsorption surface of the metallic core.