The use of ferromagnetic fluids for cooling applications represents an encouraging alternative to traditional methods; the fact that the fluid can be pumped with no moving mechanical parts, using the magnetoealoric effect. can be a great advantage for many applications where maintenance or power consumption are undesirable. A magnetic material suitable for this application has to fulfill certain requirements like tunable demagnetization temperature (Tc), high saturation magnetization (Ms) and high enough pyromagnetic coefficient (ΔM/ΔT). On this basis, the present work is focused on the synthesis of pure and Gd-doped MnxZn1-xFe2O4 nanoparticles as candidate materials for magnetocaloric pumping applications. The synthesis of the ferrite nanoparticles was carried out by a modified coprecipitation approach where the oversaturation in the reacting solution was controlled by the addition of reactants at specific flow-rates.