Superparamagnetic magnetite nanoparticles (MNPs), Fe3O 4, were synthesized via the modified coprecipitation method. The morphology of these MNPs is polyhedral. The particle size of MNPs ranged from 20 to 100 nm. For combined hyperthermia and thermoresponsive drug delivery applications, the heating element, MNPs, in the core of drug carriers should increase the temperature of the target up to 43 °C under AC magnetic field. Therefore, the heating effect of these MNPs under AC magnetic field produced by a high frequency induction heater was examined. From the results, one can see that as the weight of these MNPs increased, the higher the increase in temperature was observed. Besides, the temperature increase has reached 8.7 °C in 15 min, when 20 mg MNPs were added to 2 ml water. The preliminary temperature rise suggests that it is applicable for hyperthermia and thermoresponsive drug delivery.