• High-entropy intermetallics (HEIs) exhibit exceptional reversible hydrogen absorption/desorption at room temperature with no activation requirement and remarkable cycling stability.
• Phase boundaries, multiphase synergy, and networked/eutectic microstructures critically enhance activation performance and hydrogen diffusion kinetics in HEIs.
• Current HEIs achieve approximately 1 H/M hydrogen storage capacity, lower than BCC-structured HEAs, but suitable for moderate-capacity mobile hydrogen storage applications.
• Alloy design using valence electron concentration, atomic size mismatch, and CALPHAD thermodynamic calculations guides the development of next-generation high-performance hydrogen storage materials.