This paper presents an experimental study which demonstrates the potentiality of multifunctional heat exchangers (MHE) to carry out exothermal chemical reactions by the local control of the reactive environment temperature. Two highly exothermal chemical reactions with different kinetics (instantaneous and fast) have been investigated. The MHE is found to be very efficient in extracting the heat released by the chemical reactions. Due to its large heat transfer capacity, this process allows to increase considerably inlet reactant concentrations without thermal runaway and thus to enhance both chemical reaction conversion ratio and yield. This study also shows the limitations of the multifunctional heat exchanger for exothermal and instantaneous chemical reactions. (c) 2006 Elsevier Ltd. All rights reserved.