Preparation of mesoporous magnetic nanoparticles was achieved through modified solvothermal reaction from iron(iii) chloride hexahydrate, ammonium acetate, polyethylene glycol and ethylene glycol that were all dissolved in ethylene glycol. Their physical-chemical, structural, magnetic and morphological characterization was performed by X-ray powder diffraction, scanning electron microscopy (SEM), electrophoretic light scattering (ELS), Brunauer-Emmet-Teller (BET) analysis, superconductive quantum interferometer (SQUID) and infrared spectroscopy (FTIR). Flavonoids quercetin, miricetin and miricitrin were incorporated into prepared mesoporous magnetite nanoparticles. We examined the influence of the external and oscillating external magnetic fields on the kinetics of the release of flavonoids. The oscillating magnetic field of the desired frequencies (0.1 Hz, 1.0 Hz and 10 Hz) was generated by the alternating current generator connected to the coil. For the source of the permanent magnetic field, a magnitude 0.19 T was used. The concentration of the released flavonoids at predetermined time was monitored by ultraviolet/visible (UV / VIS) spectroscopy. It has been found that nanoparticles have a proper crystalline structure with a crystal size of 32 nm. Given the specific surface area of 16.69 m^2 g^-1, pore diameter 25.93 nm and pore volume 0.106 cm^3 g^-1 synthesized nanoparticles belong to the group of mesoporous nanoparticles. To be applied in an oscillating magnetic field, nanoparticles of magnetite must be superparamagnetic, as confirmed by the measurement of saturation magnetization. The prepared nanoparticles exhibit a good model for incorporating flavonoids, whereby the quercetin is best fitted from the chosen flavonoids. Given the structure of flavonoids this is in line with the expected. Miricetin, the most hydrophobic flavonoid of the used, and miricitrine with additional rhamnose due to steric factors, are poorly incorporated into nanoparticles. Release of flavonoids from magnetite nanoparticles under the action of permanent and oscillating magnetic fields is most pronounced at the oscillation frequency of 10 Hz.