The article describes the selection of reaction parameters for preparing magnetic nanoparticles (nanoFe3O4) by Massart's synthesis. However, the magnetic nanoparticles belong to a group of unstable systems and rapidly agglomerate. Therefore, in the second step of the synthesis encapsulation of magnetic nanoparticles usung gold nanoparticles (nanoFe3O4/Au) in the presence of a suitable stabilizer was conducted. Hence, the synthesis was carried out in the presence of 10% (wt.) solution of PVP, 0.1 M sodium citrate and 3% solution of gum arabic. Such synthesis were conducted at room temperature and at 80°C. Progress of the reaction was monitored using UV-Vis spectrophotometry. The resulting magnetic-nanogold encapsulated nanoparticles were analyzed using X-ray diffraction. What is more, for selected samples the average particle size was determined using dynamic light scattering (DLS). ...