In this research, NiFe 2 O 4 -based composite nanopowder with 0.8, 1, 1.35, 1.7 fuel-to-oxidant (F/O) ratios was synthesized by sol-gel auto-combustion method. Changes in phase constituents, microstructure and magnetic properties due to changes in F/O ratios were evaluated by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscope (FESEM) and vibrating sample magnetometer (VSM) techniques. XRD and Raman spectroscopy results show the presence of NiFe 2 O 4 , FeNi 3 , a-Fe 2 O 3 and NiO phases. The amount of nickel ferrite was increased, while the amount of FeNi 3 was decreased with increasing F/O ratio from 0.8 to 1.35. Mean crystallite sizes of the samples are in the range of 40-46 nm. FESEM studies depicted the formation of NiFe 2 O 4 particles coexisting with FeNi 3 phase. Changes in F/O ratios alter the saturation magnetization values from 37 to 60 emu/g as a result of changes in FeNi 3 and NiFe 2 O 4 amounts. Coercivity values are in the range of 135-177Oe. Graphical Abstract In this research nano-sized NiFe 2 O 4 powders with 0.8, 1, 1.35, 1.7 Fuel to Oxidant (F/O) ratios were synthesized by sol-gel auto-combustion method. FESEM studies depicted the formation of NiFe 2 O 4 particles coexisting with FeNi 3 phase. Changes in F/O ratios alter the saturation magnetization values from 37 to 60emu/g as a result of changes in FeNi 3 and NiFe 2 O 4 amounts. Coercivity values are in the range of 135 to 177Oe.