In this Letter, we assess the ability of various density functionals to correctly describe the pathway of the simple reaction LiH + NH3 -> LiNH2 + H-2, a model for hydrogen storage in recent lithium-based materials. To this aim, the ability of 27 exchange-correlation approximations for providing accurate reaction energies, activation barriers and local Bader's Atoms in Molecules properties is evaluated. Lastly, conceptual DFT is used to broaden the scope of possible relevant interpretative tools. (C) 2011 Elsevier B.V. All rights reserved.