The Web Service Business Process Execution Language (WS-BPEL) is an XML based language for describing business processes. In the last few years WS-BPEL has become the de-facto standard for orchestrating Web services and is widely accepted in industry and research. WS-BPEL processes are deployed and executed on a WS-BPEL engine which manages the control and data flow of a WS-BPEL process and handles the communication with external service partners. The goal of this diploma thesis is to describe how executing WS-BPEL process instances, especially of long-running processes can be migrated from one workflow server to another workflow server of the same type and how this is beneficial for the management of hardware resources involved in the execution of business processes. Therefore the Open source WS-BPEL engine Apache ODE has been extended with capabilities which enable the migration of WS-BPEL process instances.