The first syntheses of a series of ionic liquids based on the hexafluorouranate(V) anion are described along with their physicochemical and electrochemical properties. The green room-temperature ionic liquid, 1-ethyl-3-methylimidazolium hexafluorouranate (EMlmUF(6)), exhibits a conductivity of 7.9 mS cm(-1), viscosity of 59 cP, and electrochemical window of 2.3 V at 298 K.