In prior works, we found that hydrothermal processes that incorporate organic sulfur into Mo7 can be efficient for obtaining highly purified and stable metallic 1T-MoS2 With the hypothesis that Anderson type POMs have the structural potential to yield discrete, cluster-sized analogues of bulk 1T-MoS2 and the knowledge that NU1K itself, is refractory toward H2S, even at elevated temperature, we attempted the synthesis of isolated , cpore-confined CoMo6S24 clusters from H2S and CoMo6O24@NU1K. We found, after experimental optimization, that heating in a tube furnace at 180 o C under flowing H2S for 24h accomplishes quantitative conversion; see Supplemental Information. Caution: Inhalation of H2S can be deadly; its handling, delivery, and removal must be carefully managed. Here, H2S functions not only as a source of sulfur, but also as a reductant for converting Mo(VI) primarily to Mo(IV), while the POM serves as a spatially isolated template for the PTM.