Currently, in the field of technology monitoring, it is very important to be able to get relevant information from heterogeneous sources, especially on the World Wide Web. The coming of Semantic Web technologies promises intelligent retrieval and access to information through the use of semantic annotations based on ontologies. In a scenario of technology monitoring, agents are useful not only for handling semantic annotations to collect information, but also for automatic generation of these annotations from Web documents. In this article, we describe a new approach based on an ontology for building a multi-agent technology monitoring system. KEYWORDS Ontologies, Semantic web, technology monitoring, annotation generation, multi agent system