1-Ethyl-3-methylimidazolium (EMIm(+)) and N-butylpyridinium (BPy+) salts of the oxotetrafluorovanadate (VOF4-) and oxopentafluoromolybdate (MoOF5-) anions with low melting temperatures have been synthesized by the reactions of the corresponding fluorohydrogenate ionic liquids and metal oxide fluoride. Differential scanning calorimetry reveals that the melting points of EMImVOF(4), BPyVOF4 center dot, and BPyMoOF5 are 348, 346, and 346 K, respectively, whereas the room-temperature ionic liquid EMImMoOF(5) only exhibits a glass transition at 190 K. Density, viscosity, and ionic conductivity of EMImMoOF(5) are 1.76 g cm(-1), 86 cP, and 5.1 mS cm(-1) at 298 K, respectively. The cathode and anode limits of EMImMoOF(5) are -0.3 and +1.4 V (vs. Ag+/Ag), respectively. The molecular geometries of the VOF4- and Mo2O4F62- anions have been determined by single-crystal X-ray diffraction, the latter being obtained by the hydrolysis of MoOF5-. The two VOF4- anions in EMImVOF(4) interact with each other through two highly asymmetric V-F center dot center dot center dot V bridges with V-F and V center dot center dot center dot F distances of 1.8633(7) and 2.3786(7) angstrom, respectively. A dinuclear anion in (BPy)(2)Mo2O4F6 possesses two symmetric Mo-F-Mo bonds with Mo-F lengths of 2.1691(12) and 2.1829(11) angstrom.