This study focuses on the tense appropriability-openness relationship, defined by some as paradox. Based on an international survey of 415 manufacturing firms, we investigate how the use of different kinds of intellectual property protection mechanisms (IPPMs) affects interfirm R&D collaboration while considering partner location in the analysis as well. Our results show that the use of formal, semi-formal or informal IPPMs has different effects on openness in terms of partner variety and depth of collaboration with academic partners, value chain partners and competitors. Moreover, when considering location we uncover previously hidden appropriability-openness liaisons showing that semi-formal or informal IPPMs are mainly valid in relation to national partners, whereas formal appropriability explains international collaborations. One implication of the study is that to better understand the appropriability-openness relationship it is imperative to differentiate between national and international settings. We further suggest that the potential paradox delineating this relationship has a geographical dimension.Keywords: appropriability; intellectual property protection mechanisms; IPPMs; inter-firm collaboration; paradox of openness; R&D collaboration; international collaboration; open innovation; partner location; partner breadth; variety; partner depth; survey.Reference to this paper should be made as follows: Stefan, I. and Bengtsson, L. (2016) 'Appropriability: a key to opening innovation internationally? ', Int. J. Technology Management, Vol. 71, Nos. 3/4, Biographical notes: Ioana Stefan is a doctoral student at the University of Gävle and KTH Royal Institute of Technology. Her primary research focus is the role of intellectual property protection mechanisms in open innovation collaborations, including the investigation of appropriability-openness tensions. Aside from her doctoral studies, she is engaged in further research projects where she contributes by e.g., performing patent analyses or investigating technology trends.Lars Bengtsson is a Professor in Innovation Management at the University of Gävle, Sweden and a Docent at The KTH Royal Institute of Technology. He has published articles and books on the subjects of innovation management, knowledge integration, manufacturing strategies and outsourcing. He currently leads research focusing on open innovation, supply chain management, human lean and rapid innovators in emerging economies.