In terms of experimental techniques, 5 monohydrates were characterised by UV/IR double resonance techniques (in different laboratories in France, Germany, Japan and Spain) and 6 by FTIR spectroscopy (in Germany), all in supersonic jet expansions. 6 compounds are aromatic, 1 is a radical, 3 are ketones, 2 are alcohols. The hydrogen bond acceptor atoms include O, F, N and π-systems. do not include such an anharmonic resonance. Where the resonance remains hypothetical, the deperturbed wavenumber uncertainty (in parentheses) spans the experimentally observed main transition wavenumber. Also provided are downshifts ∆ OH /cm -1 (positive, if the complex has a lower wavenumber) from the water monomer fundamental at 3657 cm -1 .