Heat in thermal therapy can be produced by exposing superparamagnetic iron oxide nanoparticles (SPIONs) to alternating magnetic fields in order to treat cancer. In addition, Magnetic Resonance Imaging (MRI) uses SPIONs as T2 contrasts agents for diagnostic purposes. This attribute gives SPIONs potential to be used as theranostic agents in MRI – guided thermotherapy in order to visualize the concentration of the particles within the tumour and monitor the effect of the treatment. The performance of SPIONs as heating and contrast agents is highly dependent on their physical and magnetic properties. In this study, six different samples of palladium core superparamagnetic iron oxide nanoparticles (Pd – SPIONs), a formulation that has not been found in literature until today, synthesized at the Reactor Institute Delft were provided. The goal of this MSc Thesis was to determine the structural and magnetic particle parameters of Pd - SPIONs that were related with optimal heating and contrast enhancing performance in thermotherapy and MRI, respectively. For this purpose, all samples were fully characterized and their performances as heating and MRI contrast agents were investigated and compared along with commercial nanoparticles. In addition, MRI phantom and CT studies were performed using the commercial nanoparticles in order to determine whether quantification of different concentrations was possible.