Polythionite solutions Li(SO2)(n), prepared by chemical reduction of sulfur dioxide by lithium, have been investigated by classical electrochemical techniques (cyclic voltammetry, electrochemical impedance spectroscopy). The study of Li(SO2)-hexamethylphosphoramide (HMPA) solutions shows that the dithionite ion S2O42- is not electroactive, and confirms that the concentration of SO2-. is very low in these solutions. The study of Li(SO2)(n)-HMPA solutions with n > 1 allows to identify two redox couples : SO2/SO2-., and S2O4/S2O4-., and some of the homogeneous chemical reactions coupled to these electron transfers.