Abstract: Electrolyte is replenished in a fully assembled stack of fuel cells by depositing dilute electrolyte on tabs extending outwardly from an external vertical face of the stack. The electrolyte is absorbed into the cell components as it cascades off the tabs and down the face of the stack. When the electrodes and matrix layers of the stack are fully saturated the stack is heated and water is evaporated until the stack has an operable electrolyte volume and electrolyte concentration therein. In a preferred embodiment the tabs are extensions of the nonporous plates separating adjacent cells in the stack.