CdI2 is trigonal omega-like structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of fourteen CdI2 sheets oriented in the (0, 0, 1) direction. Cd2+ is bonded to six equivalent I1- atoms to form edge-sharing CdI6 octahedra. There are three shorter (3.04 Å) and three longer (3.05 Å) Cd–I bond lengths. I1- is bonded in a distorted T-shaped geometry to three equivalent Cd2+ atoms.