An anhydrous alumina (Al2O3) sol was prepared from aluminum isopropoxide and an organic solvent, using an acetic acid stabilizer. The complete conversion of the dried sol to alpha-Al2O3 was accomplished at a temperature of 950 degrees C by a single transition via gamma-Al2O3. Al2O3 that was deposited via dip coating resulted in amorphous films, even after annealing at 1100 degrees C, because of the silicon diffusion from the substrate. This phenomenon was avoided using a rapid thermal treatment in a flame after dip coating, which resulted in uniform thin films that are converted to alpha-Al2O3 via heat treatment.