The melting temperatures of [C n mpy]Cl (4 e even n e 18) were determined by a dynamic method and confirmed by differential scanning calorimetry. The latter technique was also used to measure the corresponding enthalpies of fusion. The temperatures marking the onset of decomposition of the eight ionic liquids were determined by thermogravimetry. The solidÀliquid and liquidÀliquid phase equilibria of binary mixtures of pyridine or nicotine with four ionic liquids of the 1-alkyl-3-methylpyridinium chloride family ([C n mpy]Cl with n = 4, 6, 10, 16) were investigated. The TÀx phase diagrams were measured at atmospheric pressure using turbidimetry in the (280 to 378) K temperature range. The diagrams show that pyridine is miscible in all proportions with the four studied ionic liquids while nicotine is only partially miscible with [C 4 mpy]Cl and [C 6 mpy]Cl. Data were interpreted using molecular dynamics simulations. The study illustrates, once again, the unique structural and solvent properties of ionic liquids.