Nanocrystalline Zn 0.5 Mn 0.5 Fe 2 O 4 was synthesized through the pyrolysis of polyacrylate salt precursors prepared via in situ polymerization of the metal salts and acrylic acid. The pyrolysis behavior of the polymeric precursors was studied by use of thermal analysis. The as-obtained product was characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM), electron diffraction (ED) pattern, scanning electron microscopy (SEM) and electron dispersive X-ray (EDX) analysis. The results revealed that the particle size is in the range of 15–25nm for Zn-Mn ferrites with good crystallinity. Magnetic properties of the sample at 300K were measured using a vibrating sample magnetometer, which showed that the sample exhibited characteristics of superparamagnetism.