MgFe2O4 nanocrystallites were synthesized by a sol-gel/combustion method. The thermal decomposition of the precursor and subsequent formation of MgFe2O4 were investigated by TG-DSC, FT-IR, XRD and TEM. A well-crystallized MgFe2O4 powder was obtained after annealing in air at 500 degrees C for 2 h. The average particle size of the ferrite calcined at 500 degrees C is similar to 10 nm, with a narrow size distribution. The particle size increased dramatically with the increase of calcining temperature. The saturation magnetizations of the nanocrystalline MgFe2O4 calcined at 500-900 degrees C are 9.9 and 30.6emu g(-1), respectively. (c) 2005 Elsevier B.V. All rights reserved.