This Special Issue aims to collect two different kinds of contributions:

• Articles describing how open innovation models, frameworks and findings can help address sustainability challenges within cities. They may include:
  • Research on a particular city sustainability challenge examined from the perspective of open innovation.
  • Conceptual and theoretical frameworks illustrating how open innovation can contribute to enhance the development of solutions to address sustainable development challenges in cities.
  • Empirical city sustainability research based on quantitative, qualitative, or mixed methods, addressing and illustrating the benefits of drawing on open innovation. Cases analysed by adopting a process theory approach (e.g. Langley, 2009) are particularly welcomed.
  • Comparative and analytical studies on urban cases, projects and initiatives responding to sustainable challenges with open innovation approaches.
• Empirical cases of innovation projects concerning the sustainability of cities, which can provide useful insights into open innovation practices and methodologies. They may include:
  • Urban projects and initiatives that address global sustainability challenges and are able to describe or capture peculiar aspects of open innovation in urban environments.
  • Specific solutions implemented or experimented in cities, which clearly represent the outputs (products or services) of open innovation processes oriented to global challenges and aiming at shifting towards sustainability.