Iron nickel alloy has been prepared from the mixed aqueous solution of iron and nickel nitrates. In the first step there is a co-formation of their ultra-fine mixed oxides by heating up the solution which is followed by hydrogen reduction of the co-formed oxides, at a relatively low temperature. The effect of temperature (500 to 700 °C) on the kinetics of the co-formed oxides reduction has been studied. The results indicate that it was possible to obtain different FeNi alloys through hydrogen reduction experiments carried out at 700 °C in 90 minutes. The X-Ray analysis of the co-formed oxides has shown separate peaks for Fe2O3 and NiO while the obtained alloy powder exhibited peaks with a d-spacing lying in between those of Fe and Ni diffractrograms. It is then proposed that the alloying has taken place during the reduction of the nanosized oxide particles of iron and nickel. It was noticed that the formation of iron-nickel alloys, depending on the composition, can be constituted by different crystalline structures (eg FeNi3: FCC, FeNi: Tetragonal and Fe3Ni: BCC and FCC). The average crystallite size determined through x-ray data analysis has shown to be equal to 26 nm. Total magnetization measurements conducted on the alloy samples evidenced a superparamagnetic behavior, which is a typical result for magnetic materials of considerable nanos-tructured content.