The synthesis and characterization of a new class of 1-(2,3-dihydroxypropyl)-3-alkylimidazolium bis(trifluoromethanesulfonimide) room-temperature ionic liquids (RTIL.s) with tunable water miscibility are reported. The presence of a vicinal diol substituent oil these RTILs allows for variable water miscibility, depending on the nature of the alkyl substituent oil the cation. Water-miscible, imidazolium-based RTILs with the bis(trifluoromethanesulfonimide) anion are unprecedented.