Abstract: Fuel cell liquid-liquid system comprising aqueous anolyte solution containing sulfite or bisulfite ion in high concentration recirculating through the anolyte compartment of a two electrolyte fuel cell. After converting its chemical energy to electrical energy in the cell, the spent anolyte is readily reactable to useful new products or reconstituted to fresh anolyte for re-use in the fuel cell. A class of distinctly advantageous embodiments within the general scope of the invention produces a re-usable effluent mixture of spent anolyte and catholyte to avoid the cost of handling the two effluent liquids separately, while gaining the economic advantage of maximum utilization of both fluids. The same combinable effluent characteristic makes the system tolerant to molecular diffusion or other leakage across anolyte/catholyte separating barriers.