The structure of the newly synthesized 3-cyano-1,5-diphenyl-formazans has been confirmed using UV, IR and proton magnetic resonance spectroscopy. The redox characteristics of p-Cl and o-CH3 formazans in ethanol + buffer media have been studied extensively using dc cyclic voltammetry, coulometry and large-scale controlled potential electrolysis. These compounds are oxidized in a single two-electron transfer followed by a deprotonation reaction forming the corresponding tetrazol cation. The reduction is also characterized by a two-electron process giving the corresponding dianion which is then protonated to the hydrazonocation. Good linearity is obtained between E1/2 and the pH value of the medium, which supports the proposed redox mechanisms.