A new series of monoiminated 1,2,4-triazole-based azo–azomethine dyes have been synthesized via condensation reaction of 4-amino-3-methyl-5-mercapto-1,2,4-triazole with various substituted azo-coupled salicylaldehyde. The dyes have been characterized by using FT-IR, UV–Vis and 1H NMR spectroscopic methods as well as elemental analysis. The electrochemical behavior of the dyes has been investigated by cyclic voltammetry in DMSO at five different scan rates. Solvatochromic behavior of the dyes has been also investigated in four organic solvents with different polarities. Furthermore, the 1H chemical shielding of the dyes were studied by the gauge independent atomic orbital (GIAO) method at the level of density functional theory (DFT).