This paper presents the synthesis of Al2O3 and Ni-doped Al2O3 spherical catalysts, developed by our group, with porous structures and high surface areas. The catalytic activity of the materials obtained was evaluated in the catalytic decomposition of methane, which is an attractive method for CO/CO2-free production of hydrogen, particularly for fuel cell applications. The catalysts were shown to be active and stable in relation to the catalytic decomposition of methane reaction. After the catalytic tests, characterization of the deposited carbon was carried out by transmission electron microscopy, scanning electron microscopy and Raman spectroscopy. The analyses indicated the presence of single-walled nanotubes (SWNTs) and multiwalled nanotubes (MWNTs). It was observed that the catalytic behaviour and the form of carbon produced depend on the characteristics of the sites present on the catalyst surface and on the operational conditions employed. (c) 2006 Elsevier B.V. All rights reserved.