An organization is a complex system where collaborative work takes place through formalized groups (such as internal committees, project groups, etc.) as well as informal groups (i.e., communities of practice) that may arise around common problems, interests and objectives. From this the need, widely recognized in the last years, of new technologies and tools addressing the information sharing requirements within organizations. This paper presents an experimental knowledge management tool, the ICAR Knowledge Portal, running at ICAR-CNR, a research institute of the Italian National Council of Research. The task of this tool is basically to provide a web-based environment for knowledge creation, sharing and access. With the ICAR Knowledge Portal, researchers can quickly set up their own sub-portals, create and organize knowledge items (such as news, papers, links, announcements, projects, etc.), share them within workgroups, search for a specific document or browse through a set of related documents (ontology-driven browsing).