Spinel lithium titanate (LTO; Li4Ti5O12) is widely used as an electrode material in lithium-ion batteries. We have successfully prepared a well-defined LTO specimen with atomically flat thin edges suitable for transmission electron microscopy (TEM) study. A thin wafer of rutile-TiO2 was prepared by the traditional thinning procedure for TEM specimens, while it had a damaged amorphous surface layer. By heating with LiOH·H2O, thin edge regions of the TiO2 specimen were transformed into an LTO single crystal. The direction of the LTO growth depends on the orientation of the TiO2 specimen, and the amorphous surface layer of the TiO2 specimen plays an important role in the single-crystalline growth. Copyright © 2014 John Wiley & Sons, Ltd.