The electrochemical reduction of gold(I) thiosulfate complexes was studied by differential UV spectroscopy and voltammetry on gold rotating disk electrode (RDE). In the UV spectrum of solutions, an absorption band with a maximum at 260.7 nm was detected. The presence of this band indicates the formation of the ion-pair charge-transfer complex (IPCT) of aurothiosulfate(I) anion and sodium cation {Na⁺[Au(S₂O₃)₂]^3-}. The results of polarization measurements on a gold RDE showed that electron transfer is preceded by a homogeneous chemical reaction of addition of Na⁺ cations and the formation of an electrochemical active species, an IPCT complex {Na⁺[Au(S₂O₃)₂]^3-}. The stability constants of the IPCT complex were determined: 45.2 ± 0.6 L mol^-1 (from the result of UV spectroscopy) and 41.4 ± 0.8 L mol^-1. The heterogeneous electrochemical reaction proceeds by the reductive electrochemical desorption mechanism and is described by a first-order kinetic equation. The rate-determining step of the process is desorption from the active center of the adsorbed species (S₂O₃^2- or others).