The transformation of electron structure and changes in S2O3 2- ion reactivity under the influence of different factors are required to be improved in order to control effectively the oxidation-reduction processes with their participation. In this study the S2O3 2- -containing systems: М n+ - L m- – Solv, where М n+ - Со3+, Fe3+, Cu 2+ , Zn 2+ , MoO 3+ , Cd 2+ , Hg 2+ ; L m- – F - , Cl - , Br - , NO3 - ClO4 - , SO4 2- , NCS- ; Solv – H2O, DMFA were investigated using electronic spectroscopy, 17О, 33S, 59Со, 67Zn, 113Cd, 199Нg NMR spectroscopy and EPR spectroscopy. Computer modeling executed (CNDO and MNDO) and parameters of 33 S NMR spectra of S 2- and SO4 2- ions, as well as value of electric-field gradient in the position of sulfur atoms of different origin allowed to estimate the expected line width and place of terminal and central sulfur atoms S2O3 2- in 33 S NMR spectra. Due to the optimal concentration, pH-value and temperature of solution were chosen, the 33 S NMR spectrum of thiosulfate-ion was recorded for the first time: δ=365 ppm, Δν=50 Hz for Scentral and δ=271 ppm, Δν=2500 Hz for Ssulfide . This fact opens up the possibility for quantification of S-S bonds. It allows to model the electron structure of S2O3 2- ion as well as to forecast its evolution in case of different types of binding The activation of S-S bond is based on interactions according to the principle of rigid and mild acids/bases. Based on all results mentioned above, the cases where S2O3 2- ion behaves as a bifunctional reagent were considered. It was revealed that the type of binding between S2O3 2- ion and cations here proposed correspond to the Pearson’s rule. Taking into consideration all information on S2O3 2- ion behavior in solution, the scheme of oxidation-reduction transformations caused by the homo- and heterolytic splitting of S-S bonds or electric charge transfer in metal-ligand systems is proposed