The nature of the S-H---S hydrogen-bonding interaction in the H₂S dimer and its structure has been the focus of several theoretical studies. This is partly due to its structural similarity and close relationship with the well-studied water dimer and partly because it represents the simplest prototypical example of hydrogen bonding involving a sulfur atom. Although there is some IR data on the H₂S dimer and higher homomers from cold matrix experiments, there are no IR spectroscopic reports on S-H---S hydrogen bonding in the gas phase to-date. We present experimental evidence using VUV ionization-detected IR-predissociation spectroscopy (VUV-ID-IRPDS) for this weak hydrogen-bonding interaction in the H₂S dimer. The proton-donating SH bond is found to be red-shifted by 31 cm^-1. We were also able to observe and assign the symmetric (ν₁) stretch of the acceptor and an unresolved feature owing to the free S-H of the donor and the antisymmetric (ν₃) S-H stretch of the acceptor. In addition we show that the heteromolecular H₂S-MeOH complex, for which both S-H---O and O-H---S interactions are possible, is S-H---O bound.

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