Magnetic nanoparticles, particularly iron oxide-based materials, such as magnetite (FeO), have gained significant attention as contrast agents in medical imaging This study aimsto syntheze and characterize FeO-based core-shell nanostructures, including FeO@TiO and FeO@SiO, and to evaluate their potential as tunable contrast agents for diagnostic imaging. FeO, FeO@TiO, and FeO@SiO nanoparticles were synthesized via co-precipitation at varying temperatures from iron salt precursors. Fourier transform infrared spectroscopy (FTIR) was used to confirm the presence of Fe-O bonds, while X-ray diffraction (XRD) was employed to determine the crystalline phases and estimate average crystallite sizes. Morphological analysis and particle size distribution were assessed by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) and transmission electron microscopy (TEM). Magnetic properties were investigated using vibrating sample magnetometry (VSM). FTIR spectra exhibited characteristic Fe-O vibrations at 543 cm and 555 cm, indicating the formation of magnetite. XRD patterns confirmed a dominant cubic magnetite phase, with the presence of rutile TiO and stishovite SiO in the coated samples. The average crystallite sizes ranged from 24 to 95 nm. SEM and TEM analyses revealed particle sizes between 5 and 150 nm with well-defined core-shell morphologies. VSM measurements showed saturation magnetization (Ms) values ranging from 40 to 70 emu/g, depending on the synthesis temperature and shell composition. The highest Ms value was obtained for uncoated FeO synthesized at 94 °C. The synthesized FeO-based core-shell nanomaterials exhibit desirable structural, morphological, and magnetic properties for use as contrast agents. Their tunable magnetic response and nanoscale dimensions make them promising candidates for advanced diagnostic imaging applications.