Recently HCI researchers have taken an interest in the concept of cool and how it can be harnessed in the design process. This is due to cool’s potential positive impact on adoption and the wider user experience. In this paper we explore the concept of cool and the challenges faced in the study of cool in design. We highlight the lack of rigorous research and causal understanding of cool, the social nature of the concept, and the likely need of heavy marketing strategy to achieve such status as challenges to the setting of cool as a design goal. We propose that more needs to be understood about the behaviour of cool before it can be considered an appropriate design aim.