The primary role of Open Innovation practices in economical transactions and market for technology has far been confirmed by recent literature. Open Innovation supplies a coherent rationale for why companies should promote IP co-development and sharing, in a proactive effort towards the exchange of valuable knowledge in the markets for technology and innovation. In this work, we will focus on co-patenting as a potential way to investigate the paradox of Open Innovation. The dichotomy between value-creation implications of R&D collaboration and value-appropriation challenges of IP sharing inherits its contradiction from the theories of Transaction Cost Economics: internal R&D limits transaction costs, but does not allow to access to specialist know-how available externally.