Abstract. Matching of semantic service descriptions is the key to automatic service discovery and binding. Existing approaches split the matchmaking process in two step: signature and specification matching. However, this leads to the problem that offers are not found although they are functionally suitable if their signature is not fitting the requested one. Therefore, in this paper, we propose a matching algorithm that does not use a separated and explicit signature matching step, but derives the necessary messages from the comparison of pre- and postconditions. As a result, the algorithm not only finds all functionally suitable services even if their signatures do not match, but also is able to derive the messages needed for an automatic invocation.