The temperature scanning plug flow reactor enables the investigation of reactions over a wide temperature range with a small time exposure. The experimental data that are gained by carrying out a temperature scanning experiment can be used to calculate the reaction rate of each component of the reactant mixture. The temperature scanning experiment has to be carried out in a certain procedure that has to be fulfilled in order to be able to apply the underlying theory. The influence of the heat transfer coefficients on the determination of the reaction rates was investigated. The ammonia synthesis was taken as an example. (C) 2003 Elsevier Ltd. All rights reserved.