In this diploma work, we have been investigating the influence of synthesis parameters on the morphology, size and magnetic properties of strontium hexaferrite nanoparticles. Strontium hexaferrite (SrFe12O19) has been synthesised by hydrothermal method, the purpose of which was to enhance magnetic properties (saturation magnetization, remanence and coercivity) of the investigated material in comparison to recently obtained values. By changing the temperature and time of the synthesis we were able to tailor nanoparticles' morphology and by doing so their magnetic properties have changed. Temperature and time of the synthesis dictate particle size and purity of product material, which influences its magnetic properties. Further enhancement of the magnetic properties of strontium ferrite was achieved by annealing.