<p>In this study, we successfully introduced NiCl₂ and CoCl₂ into hydrazine borane (N₂H₄BH₃, HB) via a solution mixing method, synthesizing a series of transition metal doped materials with varying weight fractions. Under open-system conditions, 15 wt% NiCl₂ doped N₂H₄BH₃ exhibited a remarkable reduction in activation energy from 107.0 (pristine HB) to 47.1 kJ mol⁻¹, along with a substantial decrease in the pre-exponential factor from 2.91 × 10¹³ to 9.92 × 10⁵ min⁻¹. In contrast, 5 wt% CoCl₂ doped N₂H₄BH₃ showed an increase in activation energy to 125.7 kJ mol⁻¹, while the pre-exponential factor increased significantly to 1.10 × 10¹⁶ min⁻¹, which may indicate an altered reaction mechanism. More notably, in a closed system, the decomposition of 15 wt% NiCl₂ doped N₂H₄BH₃ occurred rapidly at temperatures as low as 97&#xa0;°C, releasing 10.6 wt% of H₂ at 200&#xa0;°C. Despite the activation energy in the closed system being slightly higher (53.8 kJ mol⁻¹) than that in the open system (47.1 kJ mol⁻¹), the pre-exponential factor increased by more than 2 order of magnitude (from 9.92 × 10⁵ to 1.16 × 10⁷ min⁻¹), suggesting a different and more favorable decomposition pathway under confined conditions. Characterization results indicate that the formation of Ni–B species may be responsible for the enhanced catalytic behavior, enabling significant reductions in both activation energy and decomposition temperature of N₂H₄BH₃, especially under closed-system conditions.</p>