The overall objective of this research is to engineer a decision aid approach to support the identification of collaborative networks which could then constitute potential Virtual Breeding Environments. An interesting aspect of this approach is working with internet and thus considered an "open universe" of potential partners. In this perspective, the paper puts the focus on extracting essential facets of firm competences using an ontology approach. The method followed to construct the ontology is presented as well as a brief introduction on its use. This work is part of an on going project to produce cognitive aids to support decisions when seeking to form partnerships and establish VBEs.