By applying a glow discharge in bromine gas, we grew thin silver bromide layers on single crystalline silver chloride substrates. The growth process is based on a reaction between (a) silver cations that are transferred from the silver chloride substrate to the reacting surface from a silver anode and (b) bromine (and electrons) from the plasma. Essentially, the bromine plasma acts as a fluid electrolyte and supplies electrons and bromine to the silver chloride surface, which works as the anode for the glow discharge. The chemical and morphological identity of the product layers is analyzed. The growth process itself is discussed with respect to further applications for the growth of ion-conducting layers.