Recently, Web services (WSs) have evolved to a quite popular research field. Nevertheless, there are obstacles that prevent the introduction of WS provision in the wide market. Among these is the inability to represent the non-functional features of WSs, i.e. their quality-of-service. Integrating QoS features in WS profiles is to the advantage of both users and providers, as it enables QoS-aware WS selection and composition addressing the user's QoS requirements and objectives, while giving WS providers a significant competitive advantage in the e-business domain, also maximizing their resources' utilization. This paper focuses on the formulation of a QoS ontology framework that is used to support QoS-aware WS provision. It is based on work carried out in the IST-Amigo Integrated Project for Ambient Intelligence (AmI) homes, which, exploiting heterogeneous technologies and infrastructures, aims to develop an open, standardized, interoperable middleware for the provision of QoS-aware AmI WSs to domestic users.