The presence of the Catalan museums that participated in the Online Museum project in the social networks is analysed: whether they are present, in which ones, what contents they share, the way in which they communicate with the users, and their users’ response. The methodology used was based on dimensions, parameters and indicators applied in similar analysis by qualified experts; and adapted to the specifities of this study. The results show disparity and significant differences among the museums, according to their importance, their funding and the expected financial and human resources. However, they also evidence the value of being highly active and communicate quality contents. Pitifully, the most significant results refer to their low presence in social networks and the almost null implementation of web 2.0 tools. The conclusions state the challenge of improving the implementation of adequate tools, the presence in social networks and the update of the information shared through them.