The electrochemical properties of poly(4,4’-diphenylamine methylenes) and poly(4,4’-diphenylimine methines) were investigated by cyclic voltammetry. A dehydrogenation reaction occurred when poly(4,4’-diphenylamine methylenes) underwent a electrochemical reaction and transformed to poly(4,4’-diphenylimine methines). The fully oxidized poly(4,4’-diphenylimine methines) had the electrochemical band gaps of 1.60-1.72 eV, which were found to significantly smaller than those of the fully reduced poly(4,4’-diphenylamine methylenes).