The contamination of oxygenated nitrogen compounds dissolved in an organic medium containing impurities represents a serious ambiguity in all previous studies concerning the electrochemical properties of nitrogen oxides. Some of these ambiguities result also from the questionable purity of the nitrogen oxides used. In an attempt to overcome these problems, we have constructed and studied cells of the type graphite/nitrogen oxide-0.75 M LiClO4-organic solvent/Li in which high contents of nitrogen oxides permit water effects to be neglected (the solvent used were sulfolane and propylene carbonate). The cell equilibrium potential(E) and the examination of the discharge curves have allowed us to account for the highly oxidizing characteristics of NO2+ ions, E(NO2+/Li)=4.8 V, in comparison with NO+ ions, E(NO+/Li)=4.2 V. This finding agrees with our previous electrochemical studies on nitryl and nitrosyl salts in anhydrous aprotic media, e.g. standard potentials E(NO2+/NO2.)=+1.350 V and E(NO+/NO)=+0.715 V vs. the half-wave potential of a ferrocene solution at the Pt electrode. Furthermore, the medium effects on the NO+/NO and NO2+/NO2 couples have been examined in various solvents chosen for their distinctive polar character. The results have been compared with those reported previously and discussed. In addition, since the contamination of nitrogen oxides with water is the subject of numerous debates, we have reviewed the electrochemical characteristics of some nitrogen oxides in anhydrous organic media, and compared the results with those obtained when the medium contains aliquots of water.