<p>With the application of hydrogen energy across multiple fields, the development of multi-element alloys with excellent hydrogen permeation and electrocatalytic hydrogen evolution reaction (HER) performance became a key research topic in this area. To this end, this study investigated the impact of copper (Cu) doping on the microstructure, catalytic activity, and corrosion resistance of the Nb₅Ti₅₈Fe_{37–<i>x</i>}Cu_<i>x</i> (<i>x</i> = 4, 6, 8, and 10) alloy series using X-ray diffraction, scanning electron microscopy, and other techniques. The results showed that Cu incorporation significantly modified the microstructure, increased the volume fraction and size of the eutectic phase {Bcc-(Nb, Ti, Cu) and B2-(Ti, Cu)Fe}, and correspondingly optimised the hydrogen binding energy. Moreover, an increase in Cu content not only enhanced the catalytic performance in hydrogen evolution and corrosion resistance, but also improved hydrogen solubility. Nb₅Ti₅₈Fe₂₇Cu₁₀ exhibits the highest hydrogen solubility, 8.8714&#xa0;mol&#xa0;H₂&#xa0;m⁻³&#xa0;Pa^−0.5 at 673&#xa0;K. Cu doping can reduce the corrosion current density from − 3.5287 × 10⁻³ to − 3.9303 × 10⁻³&#xa0;A/cm², and the corrosion potential (<i>E</i>_corr) decreased from − 0.1591 to − 0.1923&#xa0;V. Nb₅Ti₅₈Fe₂₇Cu₁₀ exhibited the most effective hydrogen evolution catalytic activity and the lowest Tafel slope and charge transfer resistance, while Nb₅Ti₅₈Fe₂₉Cu₈ demonstrated the highest hardness of 642.16&#xa0;HV and relatively good mechanical properties. This study further confirmed that Cu doping altered the electronic and lattice structure of this alloy series, regulated its microstructure, and thereby enhanced its overall performance. These findings provided valuable theoretical insights and practical guidance for designing efficient and durable catalysts for HER.</p>