The paper considers the main laws governing processes of electrochemical silver dissolution/passivation in solutions of dicyanoargentate complexes in the presence of high-capacity (borate-phosphate-carbonate) buffers. The mechanisms of anodic processes in BPC electrolytes for silver plating were established. The composition of passivating univalent silver oxide film was determined. An original method for the calculation of the activation energy of the process is proposed. The choice of ethylenediamine as an activator of silver dissolution in solutions of dicyanoargentate complexes was justified. A difference in the mechanism of the anodic process occurring in electrolytes with addition of ethylenediamine was ascertained. On the basis of this, a silver plating electrolyte based on dicyanoargentate complexes was developed and optimized to solve the problem of activating anodes and increasing the stable-service life of buffered electrolytes for their practical use in technologies for functional silver plating.