Physical and electrochemical properties of 1-ethyl-3-methylimidazolium ionic liquids of mixed anions, (FH)(2.3)F-, BF4-, and N(SO2CF3)(2)(-), have been investigated. Molar volume shows almost linear behavior, whereas molar conductivity is decreased by mixing for the systems involving (FH)(2.3)F-, due to the enhancement of ion association in spite of the decrease in viscosity. The currents at the anode and cathode limits in the cyclic voltammogram of EMIm(FH)(2.3)F decreases with decrease in the molar ratio of (FH)(n)F-, suggesting the involvement of (FH)(n)F-, for both electrode reactions. Electrochemical stability of the BF4-TFSA mixture is unchanged by mixing.