A mechanochemical process for the synthesis of alane (AlH3) starting from lithium hydride (LiH) and aluminium chloride (AlCl3) at room temperature and the underlying reaction pathway have been studied. In contrast to a conventional process using the same two reactants dissolved in diethyl ether, our approach enables solvent-free synthesis, thereby directly leading to adduct-free alane. The method described here is quick and efficient, resulting in a quantitative conversion of all of the aluminium in the starting mixture to alane. Both the intermediate compounds formed during the reaction and the final products have been characterized by powder X-ray diffraction, solid-state 27Al NMR spectroscopy, and temperature programmed desorption analyses of as-milled mixtures. We show that excess LiH in the starting mixture (the optimum ratio is 9LiH:1AlCl3) is essential for the formation and stability of the Al-H bonds, initially in the form of alanates and, eventually, as alane. Processing of this mixture with sequential addition of AlCl3 to reach the ideal 3LiH:1AlCl3 stoichiometry appears to restrict local accumulation of AlCl3 during the milling process, thereby preventing the formation of unstable intermediates that decompose to metallic Al and molecular hydrogen. We also demonstrate that under the milling conditions used, a moderate hydrogen pressure of ca. 300 bar is required to suppress competing reactions that lead to formation of metallic Al at room temperature. Identification of reaction intermediates provides an insight into the mechanism of this solid-state reaction, which may potentially afford a rational approach towards production of AlH3 in a simple solvent-free process.