This paper presents an approach based on semantic annotation of CVs and job offers for automating recruitment on the web. The main idea consists on modeling formally the semantic content of these documents in term of their acquirements (case of a CV) or requirements (case of a job offer) using a shared ontology between recruiters and job seekers. The domain ontology built is inspired from the most significant parts of these documents (personal qualifications, diplomas and job experiences) and handle the competencies management. It describes a model of competency as well as hierarchies of topics that a competency can have. It allows the end user to explicitly enrich his document with metadata (annotations). Semantic matching between supply and demand, based on the computation of a coefficient, can be applied in a superficial or a deep way. Superficial matching deals with all acquirements/requirements mentioned explicitly by a job seeker/recruiter (a special diploma, a special job experience or a special personal qualification), whereas competency based matching deals with all competencies underlying the user’s document.