The aqua ion [W3S4(H2O)(9)](4+) (1) provides ready access to the cuboidal trinuclear [W3S4](4+) cluster as a template for the development of a new class of X-ray contrast media. The unique 1:1 cluster-ligand complex [W3S4(TTHA)](2-) (2) was isolated from the reaction of 1 with TTHA in refluxing DMF. Satisfactory levels of X-ray attenuation resulted from the three tungsten atoms, while the desired biological profile was imparted through the complexation with TTHA.