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The magnetocaloric effect of chemically synthesized Mn 0.3 Zn 0.7 Fe 2 O 4 superparamagnetic nanoparticles with average crystallite size of 11 nm is reported. The magnitude of the magnetic entropy change (ΔS M ), calculated from magnetization isotherms in the temperature range of 30 K to 400 K, increases from -0.16 J-kg -1 K -1 for a field of 1 T to -0.88 J-kg -1 K -1 for 5 T at room temperature. Our results indicate that ΔS M values are much higher than primarily reported values for this class of nanoparticles. ΔS M is not limited to the ferromagnetic-paramagnetic transition temperature; instead, it occurs over a broad range of temperatures, resulting in high relative cooling power.