Abstract: In this work the electrochemical redox reactions of three piperidine nitroxides (1-3) in methanol were investigated for the purpose of elucidating the mechanism of their electron-transfer (ET) processes. Cyclic voltammctric studies on 1-3 in acidic methanol solution have clearly demonstrated that both electrochemical reduction and oxidation show reversible ETcharacteristics. Both E_1/3^red and E_1/2^ox with approximate values of -0.28V and 0.70V respectively, indicate that these nitroxides can be regarded as good models of electron acceptors and donors. It was further found that reduction currents (RC) were considerably larger than oxidation currents (OC) under the same conditions. Moreover, RCincreased rapidly as the acidity of the medium increased, whereas OC decreased slightly with increasing acidity of the medium. These results verify that reduction of 1-3 in acidic nonaqueous solution is expected to procced rapidly and that in weak acidic medium the oxidation of 1-3 should be favored.