TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The metal substrate comprises a metal selected from gold, silver, platinum, copper or mercury (preferably gold comprising nonporous gold) or comprises a metal treated to remove a surface oxide coating.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The utilizing hydrogen gas involves consuming the hydrogen gas in a combustible engine or in a fuel cell. (M2) Further involves disassociating the R1-X' bound to the metal substrate to produce a spent compound by heating the R1-X' bound to the metal substrate or contacting the R1-X' bound to the metal substrate with ultraviolet (UV) light. (M2)/(M3) further involves reacting (a1)/(a2) respectively with hydrogen to produce a compound having a formula R1-X'H/R1-XH, thus regenerating the compound capable of producing hydrogen from (a1)/(a2) respectively. The reacting (a1)/(a2) with hydrogen involves catalytic hydrogenation. The producing hydrogen and the regenerating the spent compound occur at different locations. (M2) Also involves reacting (A) with the metal substrate to produce hydrogen gas and a spent compound (a1) comprising R2-X'H where (R2 is dehydrogenated relative to R1) and/or R3=X (R3 is dehydrogenated relative to R1). The collecting step involves consuming the hydrogen gas in a combustible engine or fuel cell. (M3) Further involves reacting the R1-XH or R'2-XH compound with the metal substrate to produce hydrogen gas and R1-X or R'2-X bound to the metal substrate respectively and disassociating the R1-X-bound or the R2-X-bound to the metal substrate to produce a spent compound (a3) comprising R1-X- or R'2-X-disassociated from the metal substrate respectively.R2,R3 = (hetero)alkyl, optionally substituted alkenyl, (aryl)alkynyl, (hetero)aryl, alkoxy, cycloalkyl, heterocyclic, alkylaryl, arylalkyl, arylalkenyl, arylene or oxyarylene group.Preferred Components: (a) Is a dimeric compound having a formula R1-X-X-R1. (A)/the liquid compound in the device is a 2-8C organothiol. (a3) Is R1-X-X-R1, R2-X-X-R'2, or R1-X-X-R'2. Preferred Device: (D1) or the assembly further includes an energy source capable of disassociating R-X' from the metal substrate to produce a spent compound (preferably a dimeric compound of formula R-X'-X'-R) when the liquid compound of formula R-X'H is used. The device or the assembly also comprises a reservoir for storing the spent compound; and a regeneration chamber to react the spent compound with hydrogen received from a source external to the device to produce a compound of formula R-X'H/R1-XH to regenerate the compound capable of producing hydrogen from the spent compound. The energy source comprises a heat source or a UV light source. The reservoir removes the spent compound from the device. The hydrogen-consuming device comprises a hydrogen combustion engine or a fuel cell. The second unit comprises a combustible engine or a fuel cell. The assembly is contained within an automobile. Preferred Definitions:    R = 2-8C alkyl, heteroalkyl, or (hetero)alkenyl group.    EXAMPLE - Gold powder (spherical, APS 5.5 - 9 micron, 99.96%, surface area of 0.05 - 0.2 m2/g) (300 mg) was placed in a chamber of the vessel (5 ml in volume). Following sealing of the vessel and evacuation of the chamber by vacuum pump, hexanethiol (1 ml) was introduced into a chamber of the vessel. Following the reaction, the contents of the vessel were analyzed with a gas chromatography connected to a reductive gas analyzer. Hydrogen gas was detected in the vessel, following the reaction, in quantities of approximately 3000 ppm.