5-Nitro-2,1-benzothiazole-3-diazonium ion reacts with various substrates (phenol, 2-naphthol, mesitylene, acetone, acetylacetone, ethyl acetoacetate) to give corresponding azo or hydrazo compounds. Characterization of the prepared compounds by means of multinuclear magnetic resonance, X-ray diffraction, and HRMS together with the study of acidobasic properties is presented, as well as significant solvatochromism. Graphical abstract: [Figure not available: see fulltext.