A monooxomolybdenum(IV) complex containing two intramolecular NH center dot center dot center dot S hydrogen bonds, (NEt4)(2)[(MoO)-O-IV-(1,2-S-2-3-t-BuNHCOC6H3)(2)], was synthesized. The trans isomer was crystallized as the major product, and the molecular structure was determined by X-ray analysis. The trans isomer was isomerized by heating in solution to give a 1:1 mixture of trans and cis isomers. Oxidation of these isomers by Me3NO afforded (NEt4)(2)[(MoO2)-O-VI(1,2-S-2-3-t-BuNHCOC6H3)(2)]. H-1 NMR analysis revealed that the dioxomolybdenum(VI) complex existed as a single isomer where both oxo ligands were trans to each of the two hydrogen-bonded thiolate ligands. The Mo-VI=O bond was effectively stabilized by the NH center dot center dot center dot S hydrogen bond via trans influence, which was determined using resonance Raman spectroscopy. These results were supported by preliminary density functional theory calculations.