The analysis of a flow-reversal reactor, constructed from a catalytic bed imbedded within two inert beds and catalysing an instantaneous reaction, shows that the main parameters that determine the maximal reactor temperature are the thermodynamic parameters, heat loss through the walls and the conductivity and length of the inert zones. We show how these parameters can be easily extracted from the experimental data of very fast reactions, and demonstrate it for ethylene and for propane oxidation. We also derive an approximation for the maximal temperature for fast or slow reactions. These approximations are compared with experimental results obtained during propane (with low feed concentration) or methane oxidation. (c) 2005 Elsevier Ltd. All rights reserved.