The capture, the structuring of the expertise or the competences of an "object" (lie a business partner, an employee and even a software component or a Web service) are of very crucial interest in many application domains, like cooperative and distributed applications as well as in cooperative e\_business applications and in human resource managment. The work that is described in this paper concerns the advertising , the classification and the discovry of competences. The foundings of the proposals that are described here after are a formal representation of competences using conceptual graphs and the use of operations on conceptual graphs for competence discovery and their possible composition.