Commercially available superparamagnetic iron oxide nanoparticles (SPION) of 12 nm are characterized with respect to their physical, magnetic, and heating properties in an alternating magnetic field. For this purpose, a specialized magnetic field setup has been developed and characterized. Particles of the waterbased ferrofluid, EMG705, and particles coated for a hydrocarbon carrier have been investigated using several techniques, including transmission electron microscopy and superconducting quantum interference device magnetometry, showing the superparamagnetic behavior of the particles. The specific absorption rate of the particles has been confirmed to have square dependency on the magnetic field strength. The difference in heating of the two samples could be explained by the difference in particles size distribution.