The mechanism and kinetics of rapid and exothermic reactions is difficult to study using conventional offline techniques. This paper deals with experimental investigations of highly exothermic and fast model reaction (cyclisation of pseudoionone) using slug flow (micro-batches) microstructured reactor (MSR). The slug flow was obtained using a cross-junction and identifying suitable inert carrier fluid (perfluorohexane) immiscible with the species participating in the reaction. MSR provided short reaction time in a continuous slug-flow that allowed catching intermediates and monitoring the kinetics. The small reaction volumes suppress the temperature rise by removing the reaction heat. The kinetics has been studied under isothermal conditions and more reliable reaction network has been proposed. Finally, the mixing within the slugs and its influence on the obtained results was accessed. This methodology has a generic nature and can be applied for a wide variety of fast exothermic homogeneous reactions. (C) 2012 Elsevier B.V. All rights reserved.