A 60 mol % K(2)SO(4)J/40 mol % V2O5 molten salt mixture was tested for electrochemical activity to determine its propensity for sulfate transport. Results of cyclic voltammetry showed a high electrochemical activity due likely to the reduction and oxidation of bulk, as opposed to minor, species. Most reductions and oxidations did not conform to diffusion-limited theory, and indicated the presence of shipping reactions. By Raman spectroscopy V(V) polymers were identified in the melt consisting predominantly of VO2(SO4)(3)(2-) and VO3- units, while VO2SO4- units were also detected. By reduction of the eutectic mixture with SO2 a V(IV) and a V(III) compound, most probably K-4(VO)(3)(SO4)(5) and K3V(SO4)(3) were isolated, as evidenced from infrared and electron spin resonance spectroscopy. These compounds might be involved in the electrochemically observed plating and stripping reactions. (C) 1999 The Electrochemical Society. S0013-4651(98)01-004-0. All rights reserved.