TlInSe2 and TlInTe2 crystallize in a tetragonal cell (space group 14/mcm) (Muller et al.). A primitive cell of these ternary crystals contains two formula units. All the Tl atoms in these compounds are univalent. The In atoms are trivalent being in a tetrahedral environment consisting of Se or Te atoms. InSe4 or InTe4 fragments of a unit cell form the chains extended along c-axis coinciding with  directions. Such chains are bonded to each other by Tl atoms.