Abstract. In the present work, we have prepared the ~10 nm superparamagnetic iron-oxide nanoparticles by means of high-temperature decomposition of iron oleate precursor. Then they were coated with silica shell to impart water-solubility and an ability to accommodate paramagnetic Gd(III)-based complexes inside silica coating. All of the prepared nanoparticles form stable in time aqueous dispersions and show good negative or/and positive contrasting effect at different magnetic field strengths (0.47, 1.41, 14.1 T). It has been also exemplifiedthat the incorporation of [Gd(TCAS)] complexes into silica shell triggers a significant increase of the transverse relaxivity of the core–shell nanoparticles. The correlation between relaxometric properties and morphology ofthe obtained nanoparticles was revealed. The non-toxicity of the obtained nanoparticles along with their ability to shorten both transverse and longitudinal relaxation rates of water protons make them good candidates for their use as dual-mode contrast agents in MRI.