The FTIR spectrum of vaporized ionic liquid has been measured with a low-temperature rare-gas matrix-isolation technique for the first time. 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, EmimTFSI, was employed as thermally vaporizable ionic liquid. The matrix-isolated IR spectrum was found to be different from either the IR spectrum of neat ionic liquid or the theoretically simulated stable 1:1 ion-pair spectrum. This observation may suggest that the vaporized ionic liquid has a certain structure different from either the liquid phase or theoretically expected ion-pair form.