Figure shows that the [RuH6] catalytic center in Ru complex hydride catalysts (Li4RuH6 and Ba2RuH6) not only outperforms the B5 site of Ru metal catalysts under the same working conditions but also produces NH3 at low temperatures. As discussed below, two inherent properties of the [RuH6] catalytic center are critical towards the observed outstanding activity at low temperatures: (a) its selectivity for chemisorbing N2 over H2 and (b) a self-adjusting mechanism of avoiding hydrogen over-saturation sustaining the N2 to NH3 conversion cycle. The catalytically active ternary hydride surface with excess Li and hydrogen (consists of two additional LiH for every six [RuH6] centers, i.e., 4[RuH6]+2[RuH7]+2Li) is energetically moderately selective towards N2 over H2 chemisorption. The model considered (110) plane of Li4RuH6, which is the most stable crystal face for this material (Figure ). The details of the Li4RuH6 active surface used for this study are in Figures and The chemisorption H2 on the Li4RuH6 active surface here can be expressed as: