NOVELTY - Catalyst composition comprises at least one precious metal, where the catalyst composition is capable of catalyzing, in the presence of a halogen ion or a mixture of halogen ions, a charging reaction and a discharging reaction in a regenerative fuel cell.    USE - The catalyst composition is useful in membrane electrode assembly, fuel cells (all claimed), and hydrogen/bromine reduction/oxidation reactions.    ADVANTAGE - The catalyst composition is cost effective, and exhibits highly acceptable life and performance.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) an anode comprising a support and a catalyst dispersed on it, where the catalyst comprises the catalyst composition;    (2) a cathode comprising a support and a catalyst dispersed on it, where the catalyst comprises the catalyst composition, or carbon powder;    (3) a membrane electrode assembly comprising the anode, the cathode and a solid electrolyte membrane disposed between the anode and the cathode, where the catalyst dispersed on the anode and the catalyst dispersed on the cathode are the same or different and are capable of catalyzing, in the presence of a halogen ion or their mixtures, a charging reaction and a discharging reaction in a regenerative fuel cell;    (4) a regenerative fuel cell-1 comprising a housing, a solid electrolyte membrane having a first surface and a second surface, disposed in the housing to partition it into the anode side and the cathode side, the anode formed on the first surface so as to connect the first surface to the anode side, and the cathode formed on the second surface so as to connect the second surface to the cathode side;    (5) a regenerative fuel cell-2 comprising a solution compartment, a gas compartment and a membrane electrode assembly disposed between the solution compartment and the gas compartment, where the membrane electrode assembly includes an anode, a cathode and a solid electrolyte membrane disposed between the anode and the cathode, and the anode faces the gas compartment and the cathode faces the solution compartment; and    (6) a fuel cell comprising the anode, the cathode and a solid electrolyte membrane disposed between the anode and the cathode.