Abstract: The need for transparent and consistent decision making in nuclear emergency management across local, regional, national and international levels is well recognised. Several decision support systems have been developed to help achieve this; but, by and large, with little consultation with potential DMs and with limited understanding of the emergency management procedures across Europe and how they differ. This work, part of a European Fifth Framework project EVATECH, considers the application of process modelling to document and compare the emergency management process in four countries. We have observed that the four process models are substantially different in their organizational structure and identified differences in where decisions are made, the management of advice and the communication network style. This papers focus is on the results of the comparison and the implications for the design and use of decision support systems.