In recent decades, sustainability has emerged as a central theme in addressing future uncertainties, intertwined with discourses on ecology, conservation, resilience and socio-ecological justice. While much scholarly attention has focused on sustainability in industrial production, design, global development and lifestyles, the relationship between sustainability and basic research remains underexplored. This paper addresses this gap by examining how sustainability concerns are integrated into scientific practice, specifically within basic research in science and engineering. Through a collaborative ethnographic research process within an interdisciplinary initiative at the University of Technology Dresden, we explore how sustainability and basic research can inform one another. Our analysis draws on qualitative methods, including interviews and group discussions and is grounded in perspectives from sociology, anthropology and Science and Technology Studies (STS), particularly valuation studies. We investigate the various meanings of sustainability as invoked in the appraisal and evaluation of basic research, pursuing the question: What is valued when basic research is deemed ‘sustainable’? Our findings are organized around four central themes: sustainability as efficiency, sustainability through flexibility, sustainability assessment as estimation and sustainability assessment as finding leverage. These themes reveal the complexities and challenges of appraising basic research in terms of sustainability.