This paper examines what motivates university researchers to patent the results of collaborative research with business firms. We provide evidence of the existence of a motivational academic patenting space comprised of: i) an industry-driven domain related to traditional-market motives (protection of inventions that will be commercialized); ii) a university-driven domain driven by various ('heterodox') motives related mostly to signalling specific research competences; iii) a 'hybrid' publicly-driven domain related to projects aligned to the research agendas of public sponsors. These three types of motivations reflect the connections between academic patenting and different types of innovation, and the roles of industry partners in proposing, financing and performing specific research projects. We use data from 16 in depth case studies of innovations developed by Dutch universities to provide preliminary empirical evidence of this typology of motivational spaces for patenting university knowledge.