The SCF synthesis method is particularly useful for controlling particle size, morphology and crystallinity of magnetic nanocrystallites. Magnetic materials owe their properties to the crystal structure and magnetic domain structure. The best performing magnetic materials can be obtained by reducing the size of the nanocrystallites. Another important material property is the magnetic anisotropy. Anisotropy hardening can be obtained for compounds with increased orbital interaction between transition metal and late elements in the periodic table. Supercritical synthesis will allow controlling the size and shape of the magnetic nanoparticles.