Electrochemical oxidation of 2,5-diethoxy-4-morpholinoaniline (1) has been studied at various pH values using cyclic voltammetry and controlled-potential coulometry. The results indicate that electrochemically generated p-benzoquinonediimine (1ox) is unstable and participates in the two types of reactions based on solution's pH. The results also show that in the acidic media, electrochemically generated 1ox via two successive hydrolysis reactions is converted to 2,5-diethoxy-p-benzoquinone (3ox), while at intermediate pH values, the Michael addition reaction of 1-1ox takes place prior to the hydrolysis reaction. Our data show that in these pH values, 1ox via two successive Michael addition reactions followed by a hydrolysis reaction is converted to 2,5-bis(2,5-diethoxy-4-morpholinophenylamino)-3,6-diethoxy-p-benzoquinone (6ox). (C) 2013 Elsevier Ltd. All rights reserved.