Inclusion complex formation of 3-octyl-1-methylimidazolium bromide (OMImBr) into alpha- and beta-cyclodextrins has been investigated with physicochemical methods and spectroscopic techniques. Spectroscopic studies like FT-IR, UV and Visible and H-1 NMR, 2D ROESY NMR were carried out to confirm the formation of inclusion complexes. The surface tension and conductivity measurements reveal the 1:1 stoichiometry of the inclusion complex. The well-known Job's method and Benesi-Hildebrand method from UV study was also applied for confirmation the host-guest stoichiometry. (C) 2018 Elsevier B.V. All rights reserved.