Objective The study aimed to develop a facile and effectual method to increase the stability of lactoperoxidase (LPO) by using its immobilization on Fe3O4 magnetic nanoparticles (Fe3O4 MNPs). Results The successful immobilization of LPO on Fe3O4 MNPs was confirmed by using Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (FE-SEM). The K-m values of free LPO and LPO immobilized on Fe3O4 were 53.19, 72.46 mM and their V-max values were 0.629, 0.576 mu mol/mL min respectively. The overall results indicated that the stability of the immobilized LPO was significantly improved compared to free LPO. The LPO immobilized on Fe3O4 (LPO- Fe3O4) retained 28% of the initial activity within 30 days at 25 degrees C whereas the free enzyme lost its activity after 7 days at the same temperature. Moreover, evaluation of the thermal stability of LPO at 75 degrees C determined the conservation of 19% of the initial activity of LPO in the LPO- Fe3O4 sample after 60 min whereas the free enzyme lost its activity after 5 min. Conclusions According to the present results, Fe3O4 magnetic nanoparticles are suitable for the immobilization of LPO.