Several regimes of the (T, x 1 , x 2 ) surface of the liquid–liquid phase diagram at or close to a nominal pressure of 0.1MPa of the ternary systems 1-hydroxyethyl-3-methylimidazolium based ionic liquids (1), [C 2 OHmim][X] ([X]=[PF 6 ] − or [BF 4 ] − or [CF 3 SO 3 ] − or [(CF 3 SO 2 ) 2 N] − ), +dichloromethane or 1,2-dichloroethane (2), +2-propanol (3) were investigated. For the first time, phase splitting in a (IL+dichloromethane) system was found and the related temperature–composition phase diagrams for all aforementioned ILs were determined. In the case of 2-propanol, partial miscibility was observed only for ILs containing the [PF 6 ] − and [BF 4 ] − anions. When the latter are involved in ternary systems, the ternary phase diagrams at ambient conditions show wide areas of total miscibility, thus revealing an unexpected and large co-solvent effect. For the ternary mixture ([C 2 OHmim][PF 6 ]+dichloromethane+2-propanol), a moderate pressure effect on the cloud point with a negative pressure–temperature slope was detected.