My project investigates current and past developments in olfaction theory (1800-today), with main focus on the notion of scientific discovery and theory development. Presenting an epistemic history of the different strategies of modelling the molecular basis and mechanisms of smell perception, it analyses how previous theoretical assumptions can become ‘ontologically blackboxed’, i.e. how theoretical assumptions are taken to represent the empirical nature of the research materials while yet lacking a sufficient experimental basis. The philosophical aim of my project is to detach philosophical discussion about scientific discovery from traditional debate about justification strategies and to suggest analysing discovery events in their own right. This, I argue, will serve better to identify and explain the novelties that characterise scientific discoveries and their impact on future studies. The way in which my project carves out a philosophically interesting notion of scientific discovery is to approach it in terms of related notions central to philosophical discussion such as the notions of observation and theory, ad hoc hypotheses, modelling and experimentation, methodology and measurement. Using the underexplored case of smell perception, these notions will be traced through the trajectory of olfactory research, showing that a historicised perspective on scientific practice is integral to understanding contemporary scientific judgment. My work is situated in the tradition of HPS (integrated History and Philosophy of Science) as Complementary Science (see Chang 2004: Inventing Temperature, OUP). The scientifically complementary goal is to provide a comprehensive history of past and present olfactory practices, shedding further light on the significance of olfaction as a thriving modelling system.