In this paper we present an autonomous mobile robot system allowing for complex collaborative interaction with non-experienced users while giving a pre-programmed tour of a public exposition. For this several modalities of man-machine communication are used simultaneously. To ensure secure and reliable operation we present a layered development approach centered on the programming system SOUL. At the Swiss National Exhibition Expo.02, ten RoboX systems will interact with hundreds of visitors per day, during a 5-month period from May 15 th to October 21 st 2002, seven days a week, ten hours per day. First tests in a real world environment and an analysis of its interaction with visitors enable us to judge the credibility of the tour-guide robot and the reliability of its operation for this outstanding event.