The thin films of spinel-LiMn2O4 were synthesized on (100) Si substrates by a sol-gel method and subsequent furnace annealing at various temperatures (300–800 °C) for 30 min. Li and Mn acetates (the atomic ratio Li/Mn of 1:2) were used as a coating solution, and dissolved in methanol with a small amount of a chelating agent. The films were confirmed to be a single phase of LiMn2O4 (space group: Fd3m) by x-ray diffraction studies. The surface morphologies of the films were examined by an atomic force microscopy, showing that the films consisted of bar-shaped crystalline parts. The area of these parts extended with increasing the annealing temperature. In the films annealed at 300 °C, the Li atomic array with slight distortions was observed in an atomically flat surface, which was associated with an unit cell with a lattice spacing of 8.195±0.005 Å on the (100) surface in spinel-LiMn2O4. © 2000 American Institute of Physics.