Recently, Semantic Web Services have been increasingly provided to search, access and manipulate information made available from autonomous and heterogeneous systems interacting in a P2P environment. Platform independency is obtained and the possibility of integrating different information sources over the Web is augmented. Service providers can act as peers on the P2P network being able to supply services and to reply to incoming service requests. Highly dynamicity and absence of a common resource conceptualization characterize the environment. As a consequence, a semantic infrastructure to organize on-the-fly distributed services and to support their automatic location is recommended. In this paper we present basic concepts and experimental evaluation of a reference architecture, SERVANT, apt to support service-based semantic search, by means of a distributed service registry.