AbstractA lightweight tank for hydrogen storage based on four kilograms of sodium alanate was designed, built and tested. An improvement in gravimetric capacity of 83% and 49% in volumetric capacity over a previous tank  was achieved. Heat evolution and temperature spikes during hydrogen absorption were studied. Due to the high specific heat of the complex hydride, the storage material itself acts as a heat sink, aiding in the heat management of the system. The first-ever radiography with fast neutrons on an operational complex-hydride based test tank was performed.