This study describes the design and development of an in situ magnetic separation process (ISMS) based on the use of ion exchange functionalized magnetic particles. ISMS as a tool for in situ product removal (ISPR) has the potential to increase the performance of a biotechnological production process comprehensively by improving the bioprocess itself and the downstream processing simultaneously. The successful implementation of this concept requires the systematic examination and optimization of the different ISMS subsystem. Hence, this report presents detailed characterization data for the magnetic particle system, the magnetic separator, and the bioprocess. For each system, specific requirements were defined and subsequently applied to identify suitable process components. In this context always economic considerations were also accounted to enable the application of this new process as cost-efficiently as possible. Especially the selection and modification of a magnetic particle system and the development of a low-cost magnetic separator were subjected to these basic criteria. For the final verification of the ISMS effects, all c ... mehromponents were brought together in a pilot scale system and used to perform cultivation with integrated ISPR. The results of this cultivation were compared to reference cultivations without ISMS to quantify the effects on the upstream processing. In addition, a detailed analysis of the efficiency of purification was performed to evaluate the consequences on the downstream processing.