In recent years, the materials research focuses toward synthesis of finer and finer microstructural features. The unique properties of nanosized particles outweigh their higher production costs. Precipitation in microemulsion is one technique, which promises to produce small particles of controlled size and morphology at reasonable cost. The present study demonstrates the synthesis of nanocrystalline alpha -Fe2O3(hematite), Mn0.5Zn0.5Fe2O4, and Ni0.5Zn0.5Fe2O4 particles in a reverse micellar microemulsion system [water-iso-octane-AOT (sodium di-2ethylhexylsulfosuccinate)]. The synthesis of alpha -Fe2O3 is performed to obtain baseline data for the synthesis of Mn0.5Zn0.5Fe2O4 and Ni0.5Zn0.5Fe2O4 in the microemulsion system. Nanosized, spherical alpha -Fe2O3, Ni-Zn ferrite, and Mn-Zn ferrite particles (20-80 nm) with very narrow particle size distribution are synthesized. Crystallization of the particles is obtained at temperatures as low as 300 degreesC.