The increase in the number of companies seeking knowledge management (KM) solutions, in order to gain significant business advantages, has created the need for a decision-aid approach in choosing appropriate KM tools. The objective of this paper is then to aid decision makers to identify the most appropriate KM tool to improve the effectiveness of their organization. To achieve this, several evaluation criteria have been identified and existing leading KM tools have been investigated. In order to rate competing systems of different vendors, we use a decision framework based on the Choquet integral aggregation, that takes into account interaction among evaluation criteria, which is generally less involved issue in other multicriteria decision making methods. Finally, a case study is given to demonstrate the potential of the methodology.