The octahedral cluster core of the anion in the structure of the title compound, (C16H36N)3[Mo6(C4H9S)6(μ3-Cl)7(μ3-S)]·2H2O, has -3 site symmetry. Two μ3-Cl atoms fully occupy positions in the cluster core, while the remaining six positions are statistically occupied by Cl and S atoms in a 1:5 ratio. The fully occupied Cl-atom positions are located on sites with 3 symmetry, and the N atom of tetrabutylammonium cation is located on a site with 2 symmetry. The structure contains also two disordered solvent water molecules, one of which is located on a threefold rotation axis and the other in a general position, both with an occupancy of 0.25. The water molecules are localized in cavities formed by the tetrabutylammonium cations and the tert-butanethiolate groups. The metal clusters are stacked in a cubic close packing arrangement along .