`titreb The software demonstration: aspects and parameters of the interaction between designers and users `/titreb This article presents an analysis of software demonstrations through observation of conversations between its designers and future users. During these meetings, the designers whose primary aim is to convince, depict the use of the software and the users express their first impressions of this usage scenario. Conversation Analysis and ethnomethodology applied to these situations reveal their interactional specificities. By using this methodology in several situations, we characterize the demonstration as structured steps and procedures. These procedures take place in a communication space-time which develops collaboration and alliances, and where technical objects evolve. Within and through these demonstration situations, we see an evolution of on one hand the relationship between designers and users, and on the other of the design process of innovative software.