In this research, the solubility of a following ionic liquids (ILs): 1-butyl-4-cyano-pyridinium bis{(triflour omethyl)sulfonyl}imide, [(BCNPy)-Py-4][NTf2], 1-hexyl-4-cyano-pyridinium bis{(trifluoromethyl)sulfonyl}imi de, [HCN4Py][NTf2], 1-hexyl-3-cyano-pyridinium bis{(trifluoromethyl)sulfonyl}imide, [(HCNPy)-Py-3][NTf2], 1-octyl-3-cyano-pyridinium bis{(triflouromethyl)sulfonyl}imide, [(OCNPy)-Py-3][NTf2], in water were experimentally determined. The experiment was carried out at a wide temperature and composition range at ambient pressure using a dynamic method. Data obtained from this experiment was satisfactorily described with the Non-Random Two-Liquid (NRTL) thermodynamic model. Based on the experiment, the influence of the IL's structure, especially, the effect of the functionalization, position (positional isomers) and alkyl chain length of the substituents of the cation as well as the structure of the cation core on mutual solubility with water was analyzed and discussed. Additionally, the experimental data presented in this research were compared to available literature data for other ILs with a similar structure. (C) 2019 Elsevier Ltd.