NOVELTY - Production of hydrogen involves catalytically decomposing a concentrated aqueous solution of potassium formate in a reaction vessel to form bicarbonate slurry and hydrogen, discharging the hydrogen from the reaction vessel, and treating a mixture comprising the bicarbonate slurry and the catalyst with an oxidizer, thus regenerating the catalyst.    USE - The processes and catalyst are useful for producing hydrogen, for storing and subsequent releasing of hydrogen, and for preparing Pd/C catalyst. Also, the potassium bicarbonate slurry in admixture with catalyst particles is useful in the heterogeneous catalytic hydrogenation of potassium bicarbonate to potassium formate (all claimed).    ADVANTAGE - The processes efficiently provide hydrogen in a storable and transportable form, based on the bicarbonate-formate cyclic system.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a process for storage and subsequent release of hydrogen, which involves: (i) catalytically hydrogenating in a reaction vessel potassium bicarbonate slurry to form a concentrated aqueous solution of potassium formate; (ii) catalytically decomposing the formate solution in a reaction vessel to form bicarbonate slurry and hydrogen; (iii) discharging the hydrogen from the reaction vessel; and (iv) treating a mixture comprising the bicarbonate slurry and the catalyst with an oxidizer, thus regenerating the catalyst;    (2) a palladium on carbon (Pd/C) catalyst with Pd loading in the range of 0.15-1.0 wt.%, where at least a portion of the palladium is present on the support in the form of sub-nanometer particles ( less than or equal to 1 nm);    (3) a process for preparing Pd/C catalyst, which involves dissolving in water a palladium (Pd2+) salt, adding to the solution heat-treated activated carbon, stirring the so-formed mixture, reducing the Pd2+ to Pd0 with the aid of formate, collecting a powder consisting of Pd/C, washing and drying same; and    (4) a power system which comprises at least one fuel cell and a hydrogen-generating unit for delivering hydrogen to the anodic compartment of the fuel cell, the hydrogen-generating unit comprising a catalyst-containing composition capable of reversible catalytic hydrogenation and dehydrogenation, which composition is in the form of potassium bicarbonate slurry and a concentrated aqueous potassium formate solution, respectively, where the hydrogen-generating unit is provided with a first feed line for introducing an incoming hydrogen stream for hydrogenating the potassium carbonate slurry and a second feed line for introducing an oxidizer into the reaction vessel for regenerating the catalyst, and a discharge line for directing a hydrogen stream generated on dehydrogenating the potassium formate solution to the fuel cell.