Thermocatalytic decomposition (TCD) of methane is an environmentally attractive approach to the production of hydrogen with reduced CO2 emissions. The perspectives of large-scale hydrogen production via TCD of natural gas (NG) are discussed in this paper. The process involves a fluidized bed reactor-regenerator system with carbon catalyst particles circulating between the apparatuses in a fluidized state. Modeling and scaling-up of a fluidized bed reactor (FBR) for TCD of NG is presented in this paper. In particular, two mathematical models, one for the bubbling fluidized bed and the other for the turbulent fluidized bed, were developed and implemented into a computer code to predict the FBR performance. These models capture most of the chemistry and physics occurring within the FBR. Model predictions compared favorably with the experimental data on methane decomposition over carbon catalyst particles. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.