Mg-Cu alloys are designed for fast hydrogen generation by precipitating an electrochemically noble phase (Mg2Cu) at the grain boundaries. The noble precipitates accelerate the hydrolysis kinetics of the alloy by synergetic action of galvanic and intergranular corrosion. The Mg-3Cu alloy exhibits a hydrogen generation rate of 5.23 ml min(-1) g(-1), which is 307 times faster than that of pure Mg (0.017 ml min(-1) g(-1)). Furthermore, the effects of annealing of the alloy on the hydrogen generation rate and the feasibility of the production of power via hydrolysis of Mg-3Cu alloy are also confirmed. The annealing of the alloy reduces the hydrogen generation rate through the decrease of precipitates, and 10 g of Mg-3Cu alloy can produce power of 7.25 W for 37 min by operation of a single cell PEMFC. (C) 2018 Elsevier B.V. All rights reserved.