Abstract: The study explores the excellent modification effect of Nb nanocatalyst prepared via surfactant assisted ball milling technique (SABM) on the hydrogen storage properties of MgH₂. Optimal catalyst doping concentration was determined by comparing onset decomposition temperature, released hydrogen capacity, and reaction rate for different MgH₂–ywt%Nb (y = 0, 3, 5, 7, 9) composites. The MgH₂–5wt%Nb composite started releasing hydrogen at 186.7°C and a total of 7.0wt% hydrogen was released in the dehydrogenation process. In addition, 5wt% Nb doped MgH₂ also managed to release 4.2wt% H₂ within 14 min at 250°C and had the ability to absorb 4.0wt% hydrogen in 30 min at 100°C. Cycling tests revealed that MgH₂–5wt%Nb could retain 6.3wt% H₂ storage capacity (89.2%) after 20 cycles. Dehydrogenation and hydrogenation activation energy values were decreased from 140.51±4.74 and 70.67±2.07 kJ·mol⁻¹ to 90.04±2.83 and 53.46±3.33 kJ·mol⁻¹ after doping MgH₂ with Nb, respectively. Microstructure analysis proved that homogeneously distributed NbH acted as active catalytic unit for improving the hydrogen storage performance of MgH₂. These results indicate SABM can be considered as an option to develop other nanocatalysts for energy related areas.