A novel way of constant hydrogen generation via Al and liquid metal eutectic GaInSn (eGIS) was proposed. The cylindrical Al with a blind hole served as a container of liquid metal to generate hydrogen via hydrolysis, while eGIS was considered a window for triggering the reaction. The microstructure, hydrolysis evolution and hydrogen production performance of the semi-solid Al-eGIS composites were investigated. The results indicated that the liquid metal embrittlement occurs when the eGIS diffuses along the grain boundaries of polycrystalline Al, which increases the reaction activity of the composites; while the formation of In₃Sn and InSn₄ secondary phases was observed, which accelerated the hydrolysis of Al. Moreover, the Al-10wt.%eGIS and Al-20wt.%eGIS composites achieved nearly 100% conversion yield of hydrolysis. Consequently, the samples were practically applied to proton exchange membrane fuel for performance measurement, with a stable power supply of 0.54 W for 110 min.