Within the frame of the deliberative democratic theory, development of ICT has been proposed as a solution to enhance discussion in large groups and foster political participation among citizens. Critics have however underlined the limits of such technological innovations which do not generate the expected diversity of viewpoints. This article highlights the limits of a Habermassian conception of deliberation which restrains it to a specific type of rational discourse and harnesses citizen’s expression within strict procedural constraints. Our case study, the DUCSAI debate, i.e. the French public debate about the location of the 3rd international Parisian airport, shows that the added value of Internet-based deliberation rests in that it offers, under specific conditions, another arena of public debate. The article shows that hybrid forms of debate can widen participant’s profile, the nature of their argumentation and their means of expression if it provides them with the opportunity to voice their concern the way they choose to do so.