In this dissertation we have proposed a generic model addressing the problem of context-aware service provisionning in persvasive computing environments,. Indeed with the latest development of communication technologies, and with the proliferation of pervasive devices, several paradigms aiming at hiding the complexity of developing a new generation of user applications are proposed. Among these paradigms, we cite the ervice-oriented paradigm. Services are suitable candidates for archieving the integration of distributed and heterogeneous applications. This thesis is an attempt for bringing into the common fold context-aware computing and Web Services. The major features of our proposed model are as follows: 1) a generic three-layered XML schema-based context model, 2) an enhancement of the actual Web Service description language with context-aware features and 3) a service provisioning approach based on the proposed description language. Additionally, three implementations of the model are presented. Finally, the model is compared with a selection of systems used in smilar areas or sharing features with our proposed model.