A novel series of ionic liquids based on the tricaprylmethylammonium cation C25H54N+, in Aliquat 336® and cetylpyridinium cation C21H38N+ in cetylpyridinium chloride incorporating sulfonate-based anions were elegantly prepared by means of ion exchange between the Cl- cation with two different anions, namely, dioctylsulfosuccinate DOSS- and dihexylsulfosuccinate HOSS-. These ionic liquids were characterised using FTIR-ATR and NMR in order to identify the molecular structures of these compounds. The physical properties of these compounds, namely refractive index and thermal properties were measured at room temperature and are reported herein. ILs incorporating cetylpyridinium cations show higher thermal stability and refractive index values as compared to Aliquat ILs due to the effects of the aromatic ring on the cetylpyridinium cation as well as the longer alkyl chain on the anion of DOSS. © 2012 American Institute of Physics.