In today’s competitive, dynamic, and changing business environment, being able to collaborate globally within and beyond the enterprise borders is critical. Inter-Organizational Collaborations (IOCs) have been proposed as a response to the characteristics of highly competitive global business environments. So far, a number of reference models, frameworks, and ad hoc architectures related to some manifestations of inter-organizational collaborations have emerged. However, less research attention has been focused on concrete cases of IOCs establishment. This paper derives a distributed service-oriented reference architecture for inter-organizational process-oriented collaboration support system from the conceptual architectures of three examined research projects in collaborative networks domain: CrossWork, ECOLEAD, and eSRA. The reference architecture covers both the IOCs’ establishment and management systematically. The proposed reference architecture is then evaluated using three other research projects: SUDDEN, MISE and Pilarcos projects. The reference architecture can serve as a foundation for analysis and design of concrete architectures of IOC systems. Manuscript profile