New 2-{5-(aryl)-6-R-3-phenyl-5,6-dihydro-4 H -[1,2.4.5]tetrazin-1-yl}benzothiazoles have been synthesized from the corresponding formazans by alkylation followed by cyclization of N -alkylderivatives. The products were characterized by 1H, 13C, NMR, IR, mass spectra and X-ray diffraction data. The electrochemical properties and antioxidant activity of obtained benzothiazoles were studied.