LaNiO3 perovskite has been successfully used as a crystalline catalyst precursor for the rapid decomposition of methane into carbon nanotubes (CNTs) and COx-free H-2. The advantages of LaNiO3 perovskite, when compared with Ni-supported La2O3 catalyst, are as follows: (1) its ability to perform at higher reaction temperature to achieve higher CH4 conversion, similar to 90% CH4 conversion at 800 degrees C vs. only 55% at 650 degrees C for NiO/La2O3 catalyst; (2) no significant deactivation of LaNiO3 catalyst; and (3) its ability to maintain catalytic activity for a long reaction time due to its ability to form CNTs even at high reaction temperature, while Ni-supported La2O3 catalyst mostly started forming encapsulating carbon species at 650 degrees C which caused rapid deactivation of catalyst. CNTs obtained from LaNiO3 perovskite have highly uniform diameter of 24 nm, which is the same size as Ni-0 particles after the reduction of LaNiO3 perovskite catalyst. Moreover, the presence of H-2 (10 vol%) in the feed stream not only reduces the deactivation rate of LaNiO3 perovskite catalyst at high reaction temperature, but also eliminates amorphous carbon on the surface of CNTs and improves the ordered graphitic structure of CNTs. (C) 2011 Elsevier B. V. All rights reserved.