The gas phase over the ionic liquid l-methylimidazolium eihanoate, [Hmim][O2CCH3] was studied by means of Raman spectroscopy. Raman spectra are presented, the species in the gas phase;Ire identified, and their bands arc assigned. The results;ire interpreted using ab initio quantum mechanical calculations that also predict vibrational spectra. The obtained data reinforce a previous interpretation, based on FT-ICR mass spectrometric data, that the vapor phase over [Hmim][O2CCH3] consists predominantly of two neutral molecules, monomeric ethanoic acid and 1-methylimidazole.