Tetratantalum nonatellurium tetraiodide oxide exhibits a one-dimensional structure containing distorted tetrahedral oxygen-centred tetranuclear clusters of Ta atoms. Each of the four shorter Ta--Ta bonds is bridged by a Te2 group, and each Ta atom is also bonded to a terminal I atom and a/~40 atom. A 1~4 Te atom connects two neighbouring clusters to form a one-dimensional chain along the b axis. The chains are held together by van der Waals interactions. Fig. I. The structure of a [TaTe~]n chain.