1-[(NO2, COOH)-substituted phenyl]-3,5-diphenylformazans were synthesized. The compounds were characterized by infrared (IR), ultraviolet-visible (UV-vis), H-1 nuclear magnetic resonance (NMR), C-13 NMR spectra, elemental analysis, and cyclic voltammetry. From the UV-vis spectra of substituted formazans it was seen that lambda (max) values were shorter than the lambda (max) value of unsubstituted formazan. It was observed that the shift values were dependent on the type and position of the substituents. A correlation between Hammett substituent coefficients and lambda (max) values was obtained. The oxidation peak potentials of substituted formazans were found more anodic than that of unsubstituted formazan. The oxidation mechanism was a single step for the NO2-substituted formazans, and two steps for COOH-substituted formazans.