In dimethylformamide containing tetramethylammonium tetrafluoroborate, copper(II) salen undergoes a three-step reduction at a glassy carbon cathode; the first voltammetric wave is attributed to reduction of copper(II) to copper(I), the second is due to reduction of copper(I) to copper metal, and the third voltammetric wave results from reduction of the salen-dianion. In the presence of adventitious water which coordinates loosely to square-planar copper(II) salen and to distorted tetrahedral copper(I) salen, the first voltammetric wave exhibits only semi-reversible behavior, which differs from that reported for other metal-salen complexes. However, removing the water causes reversibility to be achieved. Upon addition of acetic acid, a new complex is formed which exhibits an irreversible one-electron reduction; a mechanism for the formation and electrochemical behavior of this species has been formulated.