<p>This study describes the effect of sintering temperature on different properties of Fe, Ni co-doped SnO₂ nanoparticles synthesized by the co-precipitation method. Samples were prepared with various sintering temperatures ranging from 400 to 700 °C for a particular doping concentration. The influence of sintering temperature on the microstructural properties, such as crystallite size, lattice parameter, and optical band gap of the synthesized Fe, Ni co-doped SnO₂ has been studied. The samples were characterized by X-ray Diffraction, Scanning Electron Microscopy, Energy-dispersive X-ray analysis, Fourier Transformation Infrared spectroscopy, Dielectric spectroscopy, and Vibrating sample magnetometer. XRD analysis reveals that the crystalline quality of the nanoparticles increases with increasing sintering temperatures. FTIR study confirms various metal oxide bonding. The optical band gap is found to decrease with increasing sintering temperatures. It was found that the dielectric loss values increased with increasing sintering temperature. Moreover, with increasing sintering temperature, the sample shows a transition from paramagnetic to ferromagnetic phase.</p>