Product Service Systems (PSS) designers are increasingly signalling the importance of emotion. However, emotion is yet to be theoretically and empirically studied in PSS design. This paper offers a conceptual model as well as an in-depth field study of the design of an emotion-centred PSS. The paper draws on and extends appraisal theory, uses it as a lens by which to analyse ‘emotional chain reactions’ in the data, and produces implications for PSS design theory and practice.