The title compound, (C(4)H(12)N)(4)[Ta(6)Cl(18)]Cl, crystallizes in the cubic space group Fm-3m. The crystal structure contains two different types of coordination polyhedra, i.e. four tetrahedral [(CH(3))(4)N](+) cations and one octahedral [(Ta(6)Cl(12))Cl(6)](3-) cluster anion, and one Cl(-) ion. The presence of three different kinds of Cl atoms [bridging (mu(2)), terminal and counter-anion] in one molecule makes this substance unique in the chemistry of hexanuclear halide clusters of niobium and tantalum. The Ta(6) octahedron has an ideal O(h) symmetry, with a Ta-Ta interatomic distance of 2.9215 (7) A.