Supported aluminum-based complex hydrides (alanates) were investigated in view of their interaction at the interface. Nickel-containing porous carbon sheets (Ni-PCSs) were combined with various alanates, resulting in a decrease of the decomposition temperature and a reduced volume expansion upon decomposition. The interaction of alanates and alanates with Ni-PCS was observed via in situ X-ray diffraction (XRD) and found out that alanate expanded during thermolysis and Ni-PCS prevented layer changes by creating a path for hydrogen to escape from the liquid layer. The thermal desorption properties of LiAlH4, NaAlH4, and Mg(AlH4)(2) containing Ni-PCS were investigated and compared. The catalytic activity of Ni-PCS depends on the electronegativity of the cation (Li, Na, or Mg) in M(AlH4). We observed that the catalyst had stronger effects when the cations have lower electronegativity. Thus, NaAlH4, which has the lowest electronegativity value among the examined alanates, was greatly affected by the Ni catalyst, with an onset decomposition temperature decreased from 140 to 111 degrees C.