We have synthesized and characterized a series of cyclohexyl-imidazolium based ionic liquids incorporating a bis(trifluoromethanesulfonyl) amide anion. To reveal the characteristic features afforded by a flexible cyclohexyl substituent, the physicochemical properties including densities, shear viscosities, and thermal properties, were measured and compared with the respective n-alkyl-imidazolium ionic liquids. The cyclohexyl-imidazolium ionic liquids showed higher densities, higher shear viscosities, and higher glass transition temperatures than their acyclic counterparts. Using H-1 and C-13 nuclear magnetic resonance spectra, we also studied the conformational dynamics of these species. (C) 2011 Elsevier B.V. All rights reserved.