NOVELTY - An electrochemical process includes compensating for pH decrease in electrolytes by circulating a fraction of the electrolytes through a positive chamber (44) of an auxiliary cell (43), and transferring a portion of a second electrolyte which exits the negative chamber of the auxiliary cell into first electrolyte.    USE - Used for energy storage and/or power delivery.    ADVANTAGE - The process controls the pH.    DETAILED DESCRIPTION - An electrochemical process comprises maintaining and circulating electrolyte flows in a liquid system in which the active constituents are soluble in a single cell or in an array of repeating cell structures. Each cell has a positive chamber containing a positive electrode, and a negative chamber (45) containing a negative electrode. The chambers are separated by cation exchange membrane (46). The electrolyte circulating in the negative chamber of each cell during discharge contains sulfide (electrolyte 1), and the electrolyte circulating in the positive chamber during discharge contains bromine (electrolyte 2). The electrolytes in the positive and negative chambers are restored or replenished by circulating the electrolyte from each chamber to storage mechanism comprising a volume of electrolyte greater than the cell volume for extended delivery of power over a longer discharge cycle than the cell volume alone would permit. Decrease in pH in the electrolytes are compensated by circulating a fraction of the electrolyte 1 or 2 through the positive chamber of an auxiliary cell, and transferring a portion of electrolyte 2 which exits the negative chamber of the auxiliary cell into electrolyte 1. The auxiliary cell comprises a positive chamber containing a positive electrode, and a negative chamber containing a negative electrode. The electrolyte circulating through the negative chamber of the auxiliary cell is a fraction of electrolyte 2 which has been made free of bromine by electrochemical reduction. The auxiliary cell operates to oxidize sulfide ions to sulfur in which a fraction of electrolyte 1 is circulated through the negative chamber, or bromide ions to bromine in which a fraction of electrolyte 2 is circulated through the negative chamber in the positive chamber to reduce water present in electrolyte 2 to hydrogen and hydroxide ions in the negative chamber.    An INDEPENDENT CLAIM is included for a regenerative fuel cell (RFC) for carrying out the above-mentioned process, comprising a single cell or an array of repeating cell structures; storage and circulation mechanism for restoring or replenishing the electrodes in the positive and negative chambers; and a compensating mechanism for pH decreases in the electrolytes.    DESCRIPTION OF DRAWING(S) - The figure shows a flow diagram of the RFC.    Positive chamber (44)    Negative chamber (45)    Cation exchange membrane (46)