A dynamical model is proposed to describe the generation of H-2 in the Al-n + H2O reactions in order to deal with the complexity of the potential energy surface. For that purpose electronic structure Density Functional Theory and Transition State Theory computations have been carried out on the Al-17(+)center dot(H2O) system. The results are compared with the findings of previous flow-tube experiments, in which Al-17(+) is found to be highly reactive with just one water molecule; that makes this system ideal for modelling. The energy ordering in terms of the activation energies of the various processes is: cluster distortions approximate to -OH migrations < -H migrations < O-H bond breaking < H-2 release. The time -dependent results are reasonably consistent with the experiments and suggest that the lowest-lying structures of the oxo type (H2Al17O+ structures) play the most relevant role in the production of H-2. The sensitivity towards energy removal from the reacting system and the impact of tunnelling have been analysed as well as the possible role of a second water molecule as a catalyst of the water-splitting step by a Grotthuss-relay mechanism. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.