This paper deals with the integration of temporal constraints within the context of Inter-Organizational Workflows (IOWs). Obviously, expressing and satisfying time deadlines is important for modern business processes, and need to be optimized for efficiency and extreme competitiveness. In this paper, we propose a temporal extension to CoopFlow, an existing approach for designing and modeling IOWs, based on Time Petri Net models and tools. Methods are given, based on reachability analysis and model checking techniques, for verifying whether or not the added temporal requirements are satisfied, while maintaining the core advantage of CoopFlow; i.e. that each partner can keep the critical parts of its business process private