The workflow model represents the set of steps performed by different entities and their execution ordering to control and manage the carried out process on organization. In which, the structure organizational determines the division of labor in order to persons perform the organization process in an appropriated manner. In collaborative applications, this structure determines how the interaction among users, as well as between the users and the application, are carried out. For this reason, a workflow to manage the group organizational structure will be ideal. Although, workflow lacks the expressive power to represent the domain knowledge and the sequence of operations. An ontology describes the knowledge domain through concepts, relations, axioms and instances, but ontology does not specify how these entities should be used and combined. Therefore, in this paper a workflow ontology to control the group organizational structure is proposed. A case study is presented to show the use of knowledge-based workflow ontology for this structure.