Emergency Health-Care based scenarios provide the motivation to develop supporting technologies for dealing with situations where people need medical assistance because of a sudden disease or emergency. The innovative combination of intelligent agent technology, semantic Web services, peer-to-peer, and mobile computing for intelligent peer-to-peer mobile service environments is the corner stone of the CASCOM project, which aims at providing a value-added support for business services for mobile workers and users across mobile and fixed networks, especially for e-Health environments. In this paper, we describe the technical approach developed in the CASCOM project for the context-aware secure composition planning and execution of Semantic Web Services.