The hexafluorophosphate anion of 1-alkyl-3-methylimidazolium ionic liquids is responsible for their poor water miscibility. Transformation of the hexafluorophosphate ionic liquids into water miscible liquids by structural modifications in the imidazolium cation could result in new applications. Improved water miscibilities were achieved with I-alkyl ether-3-methylimidazolium hexafluorophosphate ionic liquids. Especially, ionic liquid I-triethylene glycol monomethyl ether-3-methylimidazolium hexafluorophosphate 5 showed a strongly increased water miscibility range, at 30 degrees C, which was further enhanced in the presence of ethanol as cosolvent. Besides, a complete water miscibility of 5 was observed at an elevated temperature of 50 degrees C. This knowledge may facilitate the predictive development of new task-specific ionic liquids.