XRD, N-2 physisorption, TPR, XPS, TEM and in situ thermal balance were employed to investigate the influence of calcination temperatures on the structure of Ni-Al2O3 catalysts prepared from Feitknecht compound precursor. The activity of the Ni-Al2O3 catalysts for methane decomposition to produce hydrogen and carbon nanofibers was investigated. In NiO-Al2O3 samples calcined at 573-873 K, only NiO phases were identified, while sample calcined at 1023 K, showed segregated NiAl2O4 spinel was formed. Both the interaction of NiO with Al2O3 in NiO-Al2O3 and that of Ni with Al2O3 in the corresponding Ni-Al2O3 became more complex with the increase of calcination temperature. It seems that the activity of Ni in Ni-Al2O3 for methane decomposition is dependent on the interaction of Ni with Al2O3 and the content of the corresponding Ni. (C) 2009 Elsevier B.V. All rights reserved.