The atomic structure of In3Sb1Te2 was investigated by high-resolution transmission electron microscopy (HRTEM) and the National Center for Electron Microscopy Simulation System. In3Sb1Te2 has a disordered NaCl structure; In atoms are positioned in a face-centered cubic lattice, and Sb and Te atoms are located at randomly occupied octahedral sites. However, the observed HRTEM images of the ordered In3Sb1Te2 phase show that Sb and Te atoms are located in specific positions, that is, at the center and edge of the unit cell, respectively. The atomic model of the ordered In3Sb1Te2 is confirmed by simulated images, which match the experimental HRTEM images. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3702575]