The electrochemical reduction of the title compounds, I and II respectively, was investigated by cyclic voltammetry in dimethylformamide as solvent. Each was shown to behave as do other bianthrones for which large differences in the reactivity of A and B conformations is observed. The A form is reduced to B2- in an ECE process and on the return scan B2- is oxidized sequentially and reversibly to B- and B. The B form can be detected on the third half cycle but its conversion back to A causes diminution of its reduction peak permitting evaluation of kBA, the rate constant for the B→A conversion. For I, kBA was 50 s-1 at 293 K whereas for II it was 4.5 s-1. The activation enthalpy for the reaction of I was found to be 67.8 kJ/mol and ΔS‡ is 18 J/K mol. A second reduction peak observed in an earlier study of I is suggested to have been caused by an impurity which served as a homogeneous redox catalyst.