Polycrystalline LiAlH4 transforms into polycrystalline Li3AlH6 and Al during short time (5 min) ball-milling with 3 mol% TiCl4 at room temperature; solid-state rearrangement of tetrahedral [AlH4](-) into octahedral [AlH6](3-) at ambient conditions was previously unknown; this transformation does not occur during ball-milling of pure LiAlH4 or in the presence of 3 mol% TiCl4 without mechanochemical treatment.