As shown in Figure , the TDTS moves from the transition state 4-5 (TS4-5) to TS3-4 as the temperature goes lower than the inflection point 498 K. Meanwhile, the TDI shifts from state 12 to state 0. For clarity, the inserted plot in Figure presents a schematic view of the shift in TDI/TDTS with temperature. There might be one inflection for each change in TDI/TDTS, which we can not resolve due to their proximity. Another essential feature in the catalytic path is the energy difference between state 12 and state 9. At 573 K, the free energies of states 9 and 12 are similar, and they are both likely candidates for the TDI. The energy difference between state 12 and state 9 increases with decreasing temperature, and the state 12 is TDI in the range 498 K < T < 573 K. The theoretically derived activation enthalpy (ΔHa) and TOF, and experimentally derived apparent activation energy (Eapp) and TOF are listed in Table . The value of ΔHa at 448 K is 98.2 kJ mol -1 . While at 573 K, with state 9 as TDI, the ΔHa is calculated to be 72.4 kJ mol -1 . An increase in temperature lowers the activation enthalpy and increases the TOF, agreeing well with the trends observed experimentally. The apparent activation energy for Li4RuH6 catalyst determined by Arrhenius plot is Eapp = 71.2 kJ/mol at temperatures higher than 523 K, and significantly increased value of 102.8 kJ/mol at temperatures below 523 K (Figure ). In contrast, there is no change in Eapp and other kinetic parameters for conventional Ru metal catalyst (Ru/MgO) in a wide temperature range (498-648 K). For Li4RuH6 catalyst, the energetic span and the TOF vary continuously with temperature. The temperature dependent TDI and TDTS modifications follow the entropy of intermediates and transition states. The entropy of a state is strongly affected by the adsorption/desorption of gas molecules. Such changes in the TDI or TDTS will tend to affect both ΔHa and the reaction order in gas molecules. This is beautifully captured by the analysis of the reaction order of NH3, N2, and H2 for Li4RuH6 (Figure ). The reaction orders changed from +0.3 to -0.47, 0.91 to 0.82, and -0.59 to -0.18 respectively for H2, N2, and NH3 with the decrease of temperature. These changes are stark contrast to the constant values for Ru metal catalyst (Ru/MgO), i.e., -0.23, 1.12, and -0.85, respectively for H2, N2, and NH3. It is worth noting that, although the H2 reaction orders of ternary Ru hydride catalysts decrease with the decrease of temperature, they are still higher than that of the Ru metal catalyst. Moreover, NH3 poisoning effects on the [RuH6] center lessens at lower temperatures, providing a favorable scenario for effective catalysis.