Strontium　hexaferrite　nanocomposites　were　synthesized　using　the　co-precipitation　method　in　an　air　atmosphere　at　low　temperature　and　annealed　at　temperatures　from　400　to　850　degrees　C.　The　synthesized　nanocomposites　were　characterized　by　X-ray　diffraction,　scanning　electron　microscopy,　transmission　electron　microscopy,　Fourier　transform　infrared　spectroscopy,　thermogravimetric　analysis,　and　vibrating　sample　magnetometry.　The　synthesized　phase　contained　Fe3+　and　Sr2+　ions　and　transformed　into　Fe3O4　at　400　degrees　C.　Above　600　degrees　C,　spherical　SrFe12O19　particles,　with　an　average　size　of　40　nm,　were　obtained.