Nano-particles polycrystalline Mn_0.45CexFe_2.55-xO₄; x = 0.0 and 0.1 were synthesized using the co-precipitation method and subsequently heat-treated. In each heat treatment the prepared samples have been investigated by XRD and TEM. The electric and magnetic properties for each heat treatment have been studied to produce samples with distinguishable character that can be suitably used in different technological applications. The obtained hysteresis loop of all the investigated samples belong to the Isoperm loop. The Mn_0.45Ce_0.1Fe_2.45O₄ samples with particle size (9.9 nm) are characterized by the lowest coercive field (28.87Oe) and highest TC (582 K), they can be used in medical applications. The samples Mn_0.45Fe_2.55O₄ (45 nm) after two steps of heating treatment shows a paramagnetic behavior and have the highest remenance ratio (0.236) and a very low dielectric loss (0.07). They can thus be used as memory storage and in several microwave applications. Mn_0.45Fe_2.55O₄ (50 nm) after three steps of heating treatment has the highest dielectric constant (1500), the lowest resistivity and lowest activation energy (0.38 eV), which are the suitable properties needed for the electronic devices.