The preparation of Li 11BD 4 from Al 11B 2, LiD and D 2 and several subsequent hydrogen sorption cycles according to 2 LiD + AlB 2 + 3 D 2 ↔ 2 LiBD 4 + Al starting from the desorbed state are investigated by in situ neutron diffraction. Absorption is carried out at T = 450 ° C and at p = 50 bar D 2, while desorption is performed at T = 450 ° C using a back-pressure of 1 bar. Compared to the Al free system, the absorption is observed at much lower temperatures and pressures. We attribute the increased deuterium uptake to the enhanced chemical reactivity of the elemental boron released in the dissociation of AlB 2. The desorption process on the other hand is similar to the desorption of pure LiBD 4 and seems not to be influenced by the present aluminum. The hydrogen capacity decreases from cycle to cycle, due to an incomplete re-formation of AlB 2. We attribute this to a phase separation of Al and B during the decomposition of LiBD 4 .