The service-orientated computing paradigm is transforming traditional workflow management from a close, centralized control system into a worldwide dynamic business process. This paper presents an agent-based Web service model to support inter-enterprise workflow management. In the proposed model, agent-based technology provides the workflow coordination at both inter-and intra-enterprise levels while Web services based technology provides infrastructures for messaging, service description and workflow enactment. Coordination agents and resource agents negotiate through a bidding mechanism for constructing dynamic workflow process between business partners. The agent system architecture, coordination model and related components are described. A prototype system is implemented for simulating the formation process of virtual enterprises. Our current approach integrating agents and Web services mainly focuses on communication and interaction. Our ongoing work is focusing on semantic integration in composing a dynamic workflow for inter-enterprise cooperation.