Ferrite spinels may also contain mixture of two divalent metal ions, in which ratio of these divalent metal ions may vary, are called mixed ferrite. The cations distribution of mixed ferrite significantly affects the surface properties of ferrospinels making them catalytically active. Because of their small size and large number of cations, for co-ordination sites, nanocrystallites are capable of enhancing the rate of chemical reactions and are increasingly gaining popularity as reactive nanocrystallites [1]. Among the various methods, microwave combustion technique is probably opted for homogeneity, high purity and improved characteristics. The microwave energy is an internal means of heat energy generation and conversion. The microwave energy is transformed into heat energy by strong inter- molecular friction and rises the temperature of the precursor materials suddenly. The use of microwave energy as heating source, speeds up the chemical reaction and kinetics, improve the economical viability, and reduces the energy loss [2]. Complexant organic agents can effectively chelate metal ions with varying ionic sizes. They also serve as reductant being oxidized by nitrate ions, thus working as fuel in a synthetic method named auto combustion sol-gel. Citric acid (C6H8O7) is most frequently used in producing in large variety of ferrites. It is inexpensive and is a more effective complexing agent than other complexant producing fine ferrite powder with smaller particle size [3, 4]. In this present study, NiCuFe2O4 nanoparticles was prepared by microwave assisted sol-gel auto-combustion method employing nickel nitrate, copper nitrate, iron nitrate, ammonia and citric acid as an organic chelate agent. The nanostructured samples were characterized by XRD, SEM, DRS and FT-IR. X-ray and the FT-IR revealed the formation of cobalt ferrite cubic spinel type structure. The direct band gap was estimated using Kubelka-Munk method and is obtained from the DRS.