A series of magnetic nanoparticles of ferrite complex oxides were simply prepared by using a citric acid complex method and characterized by using XRD, FT-IR spectroscopy, TEM, the BET nitrogen adsorption/desorption technique, and a vibrating sample magnetometer. The magnetic nanoparticles were used for the N-arylation of nitrogen nucleophiles to form new CN bonds. CuFe₂O₄ nanoparticles calcined at 850 °C exhibited the best activity with moderate to excellent yields under ligand-free conditions. Notably, CuFe₂O₄ is completely recoverable with an external magnet and can be reused eight times without significant loss of catalytic activity.