The analysis of past disaster response operations led to recommendations for improving disaster management, namely on the areas of situational awareness, decision support, and organizational agility. Information technologies offer solutions with the potential to answer these recommendations. This was the reason for launching the THEMIS (disTributed Holistic Emergency Management Intelligent System) project, which followed the UCD approach. THEMIS is an Intelligent System that applies Artificial Intelligence methodologies in support of disaster managers and first responders. The paper addresses the activities regarding designing and testing the user interaction of a digital prototype developed for disaster managers, describing the procedures adopted, the test conditions, test population, and the evolution of prototypes based on test findings. The paper also addresses the use of eye-tracking to support the analysis of tests, helping on the identification of user errors or problems faced while performing the tasks established in a validated test script.