TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The catalyst is transition metal and/or noble metal. The basic additive is alkaline metal hydroxide, alkaline earth metal hydroxide, alkaline metal carbonate, alkaline earth metal carbonate, quaternary tetraalkylammonium hydroxide, quaternary tetraalkylammonium carbonate, quaternary tetraalkylphosphonium hydroxide, quaternary tetraalkylphosphonium carbonate, and/or quaternary tetraalkylphosphonium alkylcarbonate. The ionic liquid contains cation, borohydride and borate, preferably metaborate.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Property: The primary ionic liquid and/or secondary ionic liquid has specified viscosity. The viscosity level is set to specified value by adding an additive. Preferred Process: The method of storing hydrogen further involes adding a basic additive to the primary ionic liqud and/or secondary ionic liquid. Preferred Composition: The cation contains moieties from hydrogen, 1-20C alkyl, 1-20C alkenyl, 1-20C alkinyl, 1-20C cycloalkyl, 1-20C cycloalkenyl, 1-20C aryl and/or 1-20C heteroaryl. The cation is pyridinium, pyrrolium, thiazolium, oxazolium and/or quinolinium, or ammonium, phosphonium and/or sulfonium, or piperidinium, pyrrolidinium and/or morpholinium, or imidazolium, benzimidazolium, pyrazolium and/or benzotriazolium, preferably trioctylmethylammonium, tetrahexylammonium, tetraoctylammonium, l-octyl-3-methylimidazolium, trihexylmethylammonium, triethylmethylammonium, tributylmethylammonium, l-ethyl-3-methylimidazolium, 1,3-dimethylimidazolium, l-butyl-3-methylimidazolium, 1,2,3-trimethylimidazolium, l-ethyl-3-methylimidazolium, l-ethyl-2,3-dimethylimidazolium, and/or l-butyl-2,3-dimethylimidazolium. The additive is amide, cyclic or polyether, acetal, ketal, polyalcohol, aromatic hydrocarbon, aliphatic hydrocarbon, dibutylether, diethylether, methyl t-butyl ether, ethyl t-butylether, 1,2-diethoxyethane, formaldehyde dimethylacetal, polyethylene glycol dimethylether, and/or polyvinyl alcohol.