NOVELTY - A catalyst which is suitable for the decomposition of formates in an aqueous reaction system and for the generation of hydrogen gas, which is free of carbon oxides side products, or for the hydrogenation of hydrogen carbonates.    USE - The catalyst and methods are useful for the decomposition of formates in an aqueous reaction system, and for the generation of hydrogen gas. Also, the system or fuel cell for is used for the storage of fuel or the raw material, and optionally for the release as needed (all claimed).    ADVANTAGE - The catalyst has improved activity, and can effectively catalyze the decomposition of formates, and the hydrogenation of the hydrogen-carbonates, respectively, by selecting the appropriate conditions.    DETAILED DESCRIPTION - A catalyst according to Formula of (IrCl(cod)(NHC)) + nP', which is suitable for the decomposition of formates in an aqueous reaction system and for the generation of hydrogen gas (H2), which is free of carbon oxide (Cox) side products, or for the hydrogenation of hydrogen carbonates (HCO3-).    cod=1,5-cyclooctadiene;    NHC=N-heterocyclic carbene, preferably 1-R-3-methylimidazolium chloride;    R=1-5C alkyl group, preferably C2 or C4 alkyl group;    n=2=4; and    P'=a 1,3,5-triaza-7-phosphaadamantane (PTA), monosulfonated ttiphenylphosphine (WTPPMS), trisulfonated txiphenylphosphine (WTPPTS), or tetrasulfonated diphenylphosphinopropane (DPPPTS).    INDEPENDENT CLAIMS are included for:    (1) a process for the preparation of the catalyst, where the stoichiometric amounts of the components of the catalyst are contacted with each other in an aqueous medium;    (2) a process for the decomposition of a formate, preferably selected from sodium formate (HCOONa), lithium formate (HCOOLi), cesium formate (HCOOCs) and potassium formate (HCOOK) in an aqueous reaction system, and for the production of hydrogen gas (H2) without COx side products, where the formate and the catalyst or the in situ mixed components are contacted with each other, at 60-100 degrees C, preferably at 80 degrees C, at pH greater than 8, preferably at pH of 8.3 plus minus 0.2, in an argon (Ar)-gas atmosphere;    (3) a process for the hydrogenation of a hydrogen carbonate (HCO3-), preferably selected from sodium hydrogen carbonate (NaHCO3), lithium hydrogen carbonate (L-HCO3), cesium hydrogen carbonate (CsHCO3) and potassium hydrogen carbonate (KHCO3) in an aqueous reaction system and for the production of a formate, preferably selected from sodium formate (HCOONa), lithium formate (HCOOLi), cesium formate (HCOOCs) and potassium formate (HCOOK), where the hydrogen carbonate and the catalyst or the in situ mixed components are contacted with each other, at an elevated temperature, preferably at 60-100 degrees C, more preferably at 80 degrees C, at a pressure of 1-1200 bar, preferably 10-100 bar; and    (4) a hydrogen storage system.