The aim of this study was the synthesis and spectroscopic characterization of amidino substituted benzimidazoles and amidino substituted benzothiazoles hydrochlorides. Targed compounds were prepared by classical reactions of organic chemistry, the Pinner reaction and uncatalyzed microwave assisted amination. From 4-chloro-3-nitrobenzonitrile 1 by microwave assisted reaction of nucleophilic aromatic substitution, 4-N-methylamino-3-nitrobenzonitrile 2 was prepared, which gave in the first stage of the Pinner reaction iminoester 3, and by introducing gaseous NH3 4-amindino-N-methyl-2-nitroaniline hydrochloride 4 is formed, which is transformed into 4-amidino-N-methyl-1,2-phenylendiamine hydrochloride 5 by reduction. Targed derivates of amidino substituted benzimidazoles 15-20 were prepared by condensation from benzaldehydes 9-14 and N-methyl-1,2-phenylendiamine hydrochloride 5, while benzimidazole derivates 21-23 are formed by condensation of 4-amidino-substituted 1,2-phenylendiamines 5-8 with 5-bromo-2-hydroxy-benzaldehyde 14. Targed derivates of amidino substituted benzothiazole hydrochlorides 26-27 were prepared by reaction of previously prepared compounds 24 and 25 with 5-bromo-2-hydroxy-benzaldehyde 14. The structures of all synthesized compounds were confirmed by means of 1H and 13C NMR spectroscopy. Targeted compounds 20, 27, 28 and 29 were characterized by UV/Vis spectroscopy in several organic solvents with different polarities. In order to explore the possible application of compounds 20, 27, 28 and 29 as optical pH sensors, UV/Vis titration of aqueous compounds solution with buffer solution with different pH were performed.