case as can be seen the composite material with the iron coating has the best reversible desorption i e 4 86 weight percent at 250 u00b0 c and 2 27 weight percent at 90 u00b0 c furthermore while iron and palladium are the preferred catalytic material a broader group comprising iron palladium platinum iridium gold and mixtures or alloys thereof is deemed by the inventors to be useful in the instant invention fig8 b is a bar graph plot of the amount of hydrogen in weight percent desorbed from composite materials produced from either the ar031 base alloy or another alloy ar026 mg 55 ni 36 mn 6 co 3 coated with various catalytic coatings on the y axis versus a different desorption temperatures on the x axis amazingly these composite materials can reversibly desorb about 1 0 to 1 1 weight percent hydrogen even at temperatures as low as 30 u00b0 c this is unheard of for a magnesium based system and allows for instant startup of hydrogen powered devices i e fuel cells hydrogen internal combustion engines etc without the need to instantaneously increase the temperature of the hydride storage material to hundreds of degrees the catalytic coating of palladium or iron should be as thin as possible and still produced the desired enhancement of the kinetics of the storage of hydrogen in the base alloy.