The structure of [(Me3C)3PI][W(CO)4I3] (I) has been detd. by x-ray diffraction. The anion of I consists of a CO-capped distorted octahedron. One iodine atom of the anion acts as donor towards the iodophosphonium cation. In I the I...I interaction is weaker and the P-I bond is stronger than in (Me3C)3PI2. Structural features of [(Me3C)3PI]+ cations are compared with those of the isoelectronic mol. (Me3C)3P:Te.