MgFe 2O 4 and ZnFe 2O 4 nanoparticles have shown relatively good biocompatibility and high superparamagnetic hyperthermia value, on par with the well-studied Fe 3O 4 nanoparticles. However, different studies have reported different values of hyperthermia on both the compounds. To elucidate which compound is superior hyperthermia compound, well-crystallined and narrow size distributed MgFe 2O 4 and ZnFe 2O 4 spherical nanoparticles (16 nm diameter) were synthesized by solvothermal reflux method and studied their magnetic hyperthermia values under identical conditions. To further enhance superparamagnetic hyperthermia in MgFe 2O 4 and ZnFe 2O 4 nanoparticles, hydrodynamic diameter of nanoparticles were reduced by completely removing the long chain oleic acid surfactant monolayer on nanoparticles and ligated short chain zwitterionic dopamine sulfonate surfactant on bare nanoparticles. These nanoparticles show good aqueous colloidal stability with zeta potential of − 32 mV. The study reveals that MgFe 2O 4 nanoparticles shows higher hyperthermia value (265 W/g) than that (216 W/g) of ZnFe 2O 4 nanoparticles at 1 mg/mL concentration under 35.33 kA/m and 316 kHz field parameters. This is high value at 1 mg/mL concentration compared to literature. High hyperthermia value arises from higher saturation mass magnetization (45.5 emu/g) of MgFe 2O 4 than that (36.5 emu/g) of ZnFe 2O 4 nanoparticles. High saturation magnetization of MgFe 2O 4 results from the preferential tetrahedral sites occupation of nonmagnetic Mg 2 + due to small ionic radii than Zn 2 + ions. If tetrahedral magnetic sublattice is occupied by more nonmagnetic cations, the net ferrimagnetic moment increases. The samples were characterized by X-ray diffraction, infrared spectra, thermogravimetry analysis, differential scanning calorimetry, field emission scanning electron microscope, zeta potential, vibrating sample magnetometer, calorimetric hyperthermia methods. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.