In this position paper we describe the actual state of the development of an integrated set of tools (called EXCOM) for automatic semantic annotation. Annotation is generally used as an operation for marking textual segments to express some morphological and syntactic information. Establishing the semantic web on a large scale implies the widespread annotation of web documents with ontology-based knowledge markup. For this purpose, tools have been developed that allow for semi-automatic annotation of web documents with ontology-based metadata. This paper describes an automatic engine for semantic annotations based on linguistic knowledge and making use of XML technologies. We are persuaded that using linguistic information (especially the semantic organization of texts) can help retrieving information faster and better in the web. The basis aim of this engine is to construct automatically semantic metadata for texts that would allow us to search and extract data from texts annotated in that.