The wireless world is a new paradigm driven by both the growing market for higher-quality higher-speed wireless services, and the ubiquitous nature of both the Internet and the PC. In order to offer uninterrupted IP service, transparent mobility and fast re-authentication are important issues for the success of wide-area wireless IP infrastructures. In this work, we describe the design of a new architecture for secure and seamless mobility (SeSMo) support in heterogeneous environments. Our proposal introduces the use of an intelligent handoff decision mechanism for the discovery and the prediction of future access routers (ARs) and the generation of new session keys. An analytical analysis of the performance of SeSMo in terms of total signalling cost is also presented