In this study novel 3-substituted-phenyl-1,5-diphenylformazans were synhesised with -CH3. -OCH3, -OH and -Br groups at o-, m- and p-positions. Their structures were elucidated with H-1-NMR, C-13-NMR and IR spectroscopy. Their UV-vis spectra indicated that their lambda(max) showed a shift amount of which was dependent upon the type and position of the substituent on the ring. There was a good correlation between these shifts and Hammel substituent coefficients. (C) 2002 Elsevier Science Ltd. All rights reserved.