The electrochemical reduction of thionyl chloride in dimethyl sulfoxide and of the thionyl chloride-lithium tetrachloroaluminate system has been studied using spectroelectrochemical techniques. Results indicate that the reduction mechanism of SOCl2 in the LiAlCl4-SOCl2 solution is essentially the same as that in DMSO. The key intermediate species in this reduction is shown to be SO+., which is produced upon reduction of SOCl2 by a one-electron transfer, followed by the dechloridation process. This species then undergoes a series of following reactions to produce the final reduction products, S and SO2, via other intermediates such as SO and S2O. At very negative potentials, reduction products of S and SO2 are shown to be produced.