Carbon materials have previously been reported to work as catalysts for hydrogen (H-2) production from hydrocarbons. Mechanisms of the catalytic behavior of graphite and carbon black (CB) have often been discussed in literature. Graphite and CB is constructed from mainly 6-membered rings with sp(2) bonds. To understand the catalytic behavior of carbon materials for H-2 production by methane (CH4) decomposition, the catalytic behavior of fullerenes with 6-membered rings and also those comprising 5- and 7-membered rings with sp(2) bonds and their associated mechanisms should be investigated. In this study, the fullerene catalyst activity has been investigated using gas chromatography and the electronic states and nanoscale structures have been analyzed. H-2 production started at 400 degrees C and the H-2 production rate gradually increased with time, and the activation energy of the fullerene for H-2 production by CH4 decomposition was found to be 166 kJ/mol. Moreover, in situ heating X-ray photon spectroscopy (XPS) measurements showed that the pi-pi* transition signal becomes stronger with increasing temperature above the threshold of 300 degrees C. The transition of the pi. electrons to pi* orbitals upon heating is expected to decompose CH 4 absorbed on fullerene. Moreover, transmission electron microscopy (TEM) analysis revealed that the generated carbon atoms from the CH4 decomposition were deposited onto the surfaces of the fullerenes, forming amorphous and layered concentric sphere carbon. Amorphous carbon is reported to not work as a catalyst for CH4 decomposition at around 400 degrees C. From XPS analysis and TEM observations of these two structures, it is anticipated that the ring structures without 6-membered rings in carbon materials with sp(2) bonding contribute to this catalytic behavior for CH4 decomposition at a low temperature of 400 degrees C. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.