Multimodal interactive systems offer a flexibility of interaction that increases their complexity. ICARE is a component-based approach to specify and develop multimodal interfaces using a fusion mechanism in a modality independent way. ICARE being reused to produce several multimodal applications, we want to ensure the correctness of its fusion mechanism. So we validate it using a test architecture based on Java technologies. This paper presents our validation approach, its results, its advantges and its limits. Keywords : test, multimodality, fusion mechanism In Proceedings of DSVIS'05 - Int. Workshop on Design Specification and Verification of Interactive Systems, to appear as LNCS, Springer Verlag, Newcastle, June 2005. LNCS proceedings are available at : http://www.springer.de/comp/lncs/index.html This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. Al...