ZnFe2O4 mixed spinel ferrite nanoparticles obtained through a citrate-nitrate combustion method. Ignited products calcined at different temperatures in 600-900ºC range and effect of calcination treatment temperature investigated. Final Products characterized by X-ray Diffraction (XRD), Fourier-Transform Infrared spectroscopy (FTIR), and Field Emission Scanning Electron Microscopy (FESEM). The average particle size calculated from Scherrer equation. Results demonstrate good agreement with total rule of increase in particle size by increasing of calcination temperature. Average particle size from X-ray data sheets for 900ºC was about 54 nm.