A focus group session is a useful tool for learning user expectations, preferences, and suggested enhancements during the design stage of a new product. This paper showcases the usefulness of using a mixed-method focus group study of first responders to examine the design of a hand-held radiation detector. The study used a survey and a semi-structured script that explored five main topics: difficulties of using radiation detection with respect to the equipment and environment; preferences for handle design; preferences for control design; preferences for screen, menu, and interface design, and instructional and maintenance issues. The focus group indicated a desire for fewer and bigger buttons to control the device, a desire for a san serif font type for the display, a request to minimize the use of abbreviations and symbols in the text display, having a color coding display bar to describe radiation levels, and a need for detailed maintenance procedures and processes. These results provide important feedback for planning the development and testing of a more ergonomic radiation detector. Relevance to industry A hand-held radiation detector to test for fissionable materials is one of the essential tools used by first responders. This paper presents the results from a focus group of first responders exploring characteristics for a more ergonomic detector.