A Th(IV) compound, [Th(TFSI)(4)(HTFSI)]center dot 2H(2)O [where TFSI = N(SO2CF3)(2)], has been synthesized and characterized using elemental analysis, thermogravimetric analysis, and vibrational spectroscopy. The analysis suggests that the TFSI anion coordinates to the metal center via the sulfonyl oxygens as well as provides evidence for the coordination of HTFSI. The voltammetric behavior of this compound has been studied in the room-temperature ionic liquid [(Me3NBu)-Bu-n][TFSI], and results show that Th(IV) is reduced to Th(0) in this ionic liquid in a single reduction step. Analysis of cyclic voltammograms shows that an insoluble product is being formed at the electrode surface, which is attributed to the formation of ThO2 by reaction with water. The E value for the reduction of Th(IV) to Th(0) has been determined to be -2.20 V (Vs Fc(+)/Fc; -1.80 V vs SHE). A comparison of this E value with those obtained for Th(IV) reduction in a LiCl-KCI eutectic (400 degrees C), water, and nonaqueous solvents shows that the reduction in [Me3N(n)Bu][TFSI] is easier to accomplish than that in these other solvents.