Cyanic
complexes of some metals with incomplete number of ligands have a catalytic effect on the electroreduction of dicyaaoargentate in aqueous solutions. The concentration profiles of the electrolyte species in the diffusion layer adjacent to the cathode were calculated as a function of the distance from this cathode during the electrolysis in the presence of the catalyst-tricyanocuprate. It follows from the calculation that this catalytic effect is related with a decrease in the free cyanide concentration in the diffusion layer at the cathode. It was established that the retardation in the middle of the cathodic voltammogram of silver reduction in the dicyanoargentate solutions at constant concentration alvays occurs at nearly the same free cyanide concentration adjacent to the electrode, just outside the double-layer. That confinns the statement that the rate of silver reduction from dicyanoargentate solution in the considered potential range is simultaneously determined by heterogeneous chemical reaction (cyanide ions participate in the passivation of the cathode surface) and the diffusion of the dicyanoargentate.