Abstract. Wikis have demonstrated how it is possible to convert a community of strangers into a community of collaborators. Semantic wikis have opened an interesting way to mix web 2.0 advantages with the semantic web approach. P2P wikis have illustrated how wikis can be deployed on P2P wikis and take advantages of its intrinsic qualities: fault-tolerance, scalability and infrastructure cost sharing. In this paper, we present the first P2P semantic wiki that combines advantages of semantic wikis and P2P wikis. Building a P2P semantic wiki is challenging. It requires building an optimistic replication algorithm that is compatible with P2P constraints, ensures an acceptable level of consistency and generic enough to handle semantic wiki pages. The contribution of this paper is the definition of a clear model for building P2P semantic wikis. We define the data model, operations on this model, intentions of these operations, algorithms to ensure consistency and finally we implement the...