The performance of a metal hydride reactor is highly dependent on its transport process. It is important to know how the transport process affects the performance, therefore two key parameters-heat transfer controlled reaction rate and mass transfer controlled reaction rate were introduced to explain this kind of effect. Moreover, a brief discussion about how to use the new parameters was given. In order to analyze the reactor performance and heat/mass transfer characteristics, a non-local thermal equilibrium model describing the actual adsorption process was formulated, and numerical simulations were carried out. Then the two parameters were applied for the same purpose. The result of the parameter analysis coincided well with that of the numerical simulation, which approved the validity of the two parameters in identifying heat and mass transfer characteristics of the metal hydride reactor. (C) 2007 Published by Elsevier Ltd. on behalf of International Association for Hydrogen Energy.