Sustainability has become an increasingly important aspect for companies to consider. Not only is it necessary to comply with laws and regulations that encourage corporate sustainability, but it has also become a way for companies to gain competitiveness. Historically, companies have primarily adopted so called closed innovation models focused on internal resources and capabilities, in order to generate competitive advantages. However, in a world characterized by rapidly changing demands and high product complexity, the internal capabilities of companies are challenged, which have led firms to explore other collaborative models of innovation. This trend is referred to as open innovation and it implies that companies open up their innovation process in order to utilize external knowledge and share their unutilized ideas. This thesis seeks to explore the sustainability-related implications of open innovation by understanding opportunities and challenges related to adopting an open approach for innovation projects that aim to enhance sustainability. Furthermore, it adopts a contingency perspective through which it seeks to examine factors affecting the sustainability-related performance of open innovation projects. The study is based on empirical data obtained through six semi-structured interviews in a Swedish state-owned enterprise within the air transport industry. The research finds that an open approach for sustainability-oriented innovation projects leads to increased creativity, increased access to knowledge and reduced duration, but that they are challenged by a high degree of complexity. Furthermore, the findings suggest that the sustainability performance of open innovation projects is moderated by three factors: the management of the project, the dedication of the individuals involved and the absorptive capacity of the team. The study argues that in order to enhance sustainability performance of innovation projects, these factors must be adjusted according to the openness of the project. By exploring the context dependencies of open innovation for sustainability purposes, the study contributes to develop a broader comprehension of the contextual characteristics of open innovation as well as its relevance for sustainability.