(Li,Mn) ferrites (LMFs; LiyMn2yFe3-3yO4+delta, y = 0.27-0.75, delta = 0.01-0.04) were synthesized by solid-state reaction of ultrafine maghemite (gamma-Fe2O3) with lithium manganese spinel (LiMn2O4) at 650 degrees C. For y less than or equal to 0.5, the LMFs were synthesized in a He gas stream; for y > 0.5, the LIMFs were formed in an air stream at 650 degrees C. In the formation of LMF (y = 0.44), release of oxygen gas was observed at 460 and 650 degrees C in a He gas stream. The oxygen release at 460 degrees C was accompanied by the reaction of LiMn2O4 with gamma-Fe2O3, and the release at 650 degrees C was due to the reaction of the formed LMF and alpha-Fe2O3. The deviation of lattice constant from Vegard＇s Law was largest at y = 0.5, where all Mn ions were trivalent.