An investigation of hydrogen generation by the hydrolysis reaction of Al-Bi alloys in different media (pure water, 1 M NaCl solution, methanol, and ethanol) was performed at room temperature. The results show that the media have a great effect on the hydrolysis of Al-Bi alloys. In 1 M NaCl solution and in pure water, Al-16 wt % Bi alloy presents the maximum conversion yields at 92.75% (970 mL g(-1)) and 89.88% (930 mL g(-1)), as well as first 5 min hydrogen generation rates of 92 and 46 mL min(-1) g(-1), respectively. However, the hydrolysis of the ball-milled Al-Bi alloys in methanol and ethanol corresponds to only a little or even no hydrogen production. The hydrolysis mechanism of the Al-Bi alloys is based on the microgalvanic cell between the anode (Al) and cathode (Bi), so the high ionic conduction of the media plays an important role in improving the Al reactivity. Bi can activate Al, and a higher content of Bi metal can accelerate the hydrolysis rate of Al. The scanning electron microscopy images and energy dispersive X-ray results showed that the shape of Al particles changes from the initial round to platelet, and the mean size first increases markedly after being milled. Then, with a prolonging of the milling time, the Al platelet ruptures, and the mean size decreases. So, the Bi distribution remains uniform with increasing ball-milling time and results in the higher reactivity of the milled alloys.