A series novel formazans (3a-3d), having -H, -Cl, -Br, -F at para-position, were synthesized from phenylhydrazone derivatives (1a-1d) with diazonium salts of 4-methoxybenzenamine (2). Products were obtained in 56-72% yields. Elemental analysis and spectroscopic characterization tools such as FT-IR, H-1 NMR, C-13 NMR and LC-MS, were applied to ascertain the structures of the target compounds. UV-Vis absorption spectra of the compounds were studied. The electrochemical properties were performed by cyclic voltammetry measurement. In the last step of the research, antiproliferative activities of the novel formazans derivatives were investigated in different three cancerous cell lines and the obtained results were comprehensively discussed. (C) 2020 Elsevier B.V. All rights reserved.