The MgAl2O4 nanocrystalline powders with 0.5 mol% concentration of Cr3+ ions were prepared using modified Pechini method. Stoichiometric amounts of magnesium nitrate (99.99%) and aluminum nitrate (99.99%) were dissolved in aqueous citric acid and ethylene glycol solution to give the appropriate molar ratio 1:2:16:6.5 of all reactants. Subsequently chromium nitrate was added into the precursor solution. After that solution were ultra- sonically stirred for 2 h and then placed into dryer for 3 days at 80 °C. In that way obtained brown polyester resins were heat-trea- ted at different temperatures (700–1200 °C) in electric oven under air atmosphere for 16 h. The structure evolution studies of the resulting Cr3+:MgAl2O4 nanopowders were characterized using XRD powder diffraction and TEM microscopy.