Boron-and nitrogen-based materials have shown to be attractive for solid-state chemical hydrogen storage owing to gravimetric hydrogen densities higher than 10 wt% H. Herein, we report a new derivative of hydrazine borane N 2 H 4 BH 3 , namely lithium hydrazinidoborane ammoniate LiN 2 H 3 BH 3 ·0.25NH 3. It is easily obtained in ambient conditions by ball-milling N 2 H 4 BH 3 and lithium amide LiNH 2 taken in equimolar amounts. Both compounds react without loss of any H atoms. The molecular and crystallographic structures of our new compound have been confirmed by NMR/FTIR spectroscopy and powder X-ray diffraction. The complexation of the entity LiN 2 H 3 BH 3 by some NH 3 has been also established by thermogravimetric and calorimetric analyses. In our conditions, LiN 2 H 3 BH 3 ·0.25NH 3 has been shown to be able to release H 2 at temperatures lower than the parent N 2 H 4 BH 3 or the counterpart LiN 2 H 3 BH 3. It also liberates non-negligible amounts of NH 3 at temperatures lower than 100 • C. This is actually quite detrimental for chemical H storage, but alternatively LiN 2 H 3 BH 3 ·0.25NH 3 might be seen as a potential NH 3 carrier.