Recently, we have demonstrated that the dehydrogenation of NaAlH4 can be carried out with sufficient kinetics even at a hydrogen back pressure of 4 bar, which is needed for a proton exchange membrane (PEM) fuel cell [10]. In this contribution the influence of hydrogen back pressure in the range of 0.2 up to 5 bar and catalyst concentration in the range between 1 and 5 wt.% overall catalyst concentration on the dehydrogenation of Zr–Ti codoped NaAlH4 is investigated in detail. The influence of the hydrogen back-pressure is significant in the 2nd dehydrogenation step. The catalyst concentration influences both kinetics and storage capacity. Rate constants as a function of the temperature and hydrogen back-pressure and activation energies of the dehydrogenation of NaAlH4 to Na3AlH6 at 1 bar and 4 bar hydrogen pressure are calculated from isothermal dehydrogenation experiments.